The three main nation state storylines converge at this point. If you aren’t sure what’s going on, reading one of the starting cities will help catch up the story.
Following Blackburn's lead, the player arrives at the Waking Sands, the meeting place of the Path of the Twelve. There, he meets their leader, Minfilia, who claims to understand what happened earlier. To prove it, she asks the player to use the power of the "Echo" to see her past.

Upon doing that, the player sees a past conversation held on that same hall. Minfilia then explains that many people have been "gifted" with that power after witnessing a starshower, and that the Path of the Twelve is an organization that offers a meeting place for those people and strives to bring peace to Eorzea, offering the player the chance to join. After joining, the player learns a bit more about the Echo and is directed to Lady Tataru, to register himself as member of the Path and choose a Path Companion.
Not long after, a party of sylphs enter into the Waking Sands asking for help, claiming that their home, Moonspore Grove, is being invaded by imperial soldiers from Garlemald. Lady Minfilia then gives her first task to the player: Investigate the Black Shroud with their Path Companion.

Arriving at Camp Nine Ivies, the player is greeted by several sylphs telling that Moonspore Cove has been invaded, and while they were able to escape, their children - "podlings" - will soon be found and killed by the invaders. Since the whole area is full of imperial troops and war machines, the player must sneak his way to the Groove, avoiding contact with the Garleans and ultimately saving a few podlings.
Later on, Minfilia has a new assignment: The player must visit the Ashcrown Consortium in Gridania, as they need help.

Arriving there, he learns about the history of Eorzea's crystal trade and how until recently most of the realm's crystals have been obtained by negotiating with beast tribes. However, ever since the beings known as Primals appeared, the tribes refuse to sell more shards, as they are crucial part of the summoning process, and therefore crafters are facing an increasingly higher increase of demand with not enough supply of crystals.
The player then is directed to an Amalj'aa excavation site to negotiate, where they find an Ashcrown party already engaged in negotiations with the Amalj'aa and the Ixali. Their leader explains that both tribes are on the verge of summoning their "Primals", which, if they are successful, would mean the death of all those in the mesa caves. After either parley or fighting, the tribes are convinced to stop their rituals, however before negotiation can begin about the crystals issues, a strange creature that the sylphs call "Ascian" appears and frightens the remaining beastmen.

Back into Ashcrown Consortium, Sylphs claim they may be able to persuade the Ixal into resuming crystal trade with them, but will need "unaspected crystals" - pure crystals devoid of any elemental aspect, perfect for the Primal summoning rituals. To get them, one must simply travel to the far away land of Mor Dhona and bury a crystal there for a time; it will quickly be drained of their elemental energy by the mysterious force said to slumber there.

Upon returning to the Consortium, the sylphs mention mysterious figures known only as "Paragons," whom they claim were the ones who originally taught the beast tribes how to summon the Primals from the aetherial void.
Back at the Walking Sands, however, the player learns about an imperial message sent to the Eorzean city-states; according to it, the beast tribes are the enemies of Eorzea and mean to summon their "eikons" for their own means, and calls all city states to accept Imperial Rule and fight against the beast tribes, in exchange of protection against the Primals. Minfilia adds that because of their ability to communicate with the tribes, all walkers will be branded by the Empire as heathens.

After a conversation with his/her Path Companion, the player decides to assist Lady Minfilia in her quest to bring the beast tribes to their side, and travels to the Amal'jaa stronghold to try negotiating with the tribe elders.
However, before reaching the center of the stronghold, they are spotted and captured by the Amal'jaa, being put in a cell with several other prisoners. Soon, every captive is led to a large clearing, where the Primal Ifrit is summoned for a "cleansing" ritual - brainwashing via magical blue flames. All the other prisoners are affected by the spell, and are ordered to attack the player. Since they are not enemies, they must not be killed - some can be brought to their senses via parley, others have to be attacked.

Ifrit remains silent during the whole confrontation, but as soon as it ends, he starts making several cryptic questions, concluding with the revelation that the player and companion, too, can summon their own Primal, as well as everyone else with the gift of the Echo, and let the player escape upon promising to never summon one and feigning loyalty to Ifrit.
A strange distress call is caught on the Path Linkpearl, and no one knows who was responsible for that, only their location. The player is then asked to go to the signal origin and search for the source.
Reaching camp Nine Ivies, their Path Companion is spotted speaking with a group of Soldiers, who claim to be part of the Ala Mhigan Resistance. It seems that one of the members of the resistance was the deceased brother of the player's Path Companion. The soldier also mentions that one of their scouts is missing and is being chased by the Empire, and the player must rescue him.

Back in the Merchant Wards, a group of members from the Ala Mhigan Resistance are speaking with the Antecedent, preparing a special operation against the Empire. The group is planning to steal one of the empire's airships to drive then away from Ala Mhigo. Since the city state is under heavy guard and such mission would be nigh impossible, the target is the least guarded area of Silvertear Falls in Mor Dhona.

The player agrees to help the resistance and makes his way to camp Revenant's Toll in Mor Dhona, only to find a trio of imperial soldiers attacking the place and being called back to their airship. The player follows the group for a while, until they get reinforcements from one of their heavy magitek machinery, an Imperial Juggernaut.
After defeating them, the player walks until finally reuniting with his/her Path Companion, only to find that all resistance members have been slain by a single man - the Imperial Legatus, Gaius van Baelsar. He easily knocks out the Path Companion with a shot, but before he is able to kill off the player, Yda, Papalymo, Y'shtola and Thancred arrive to stop him. But Gaius proves too much for the four as calls a blast from the cannons of the Imperial Dreadnaught and disappears in the smoke.

The player wakes up in a cave, quickly noticing he is actually seeing the past. Some children are grouped there, and Garlean Soldiers come in and start uttering strange verses, brainwashing the children into believing the beast tribes of Eorzea and their Primal must be killed.

The player once again collapses and wakes up back in the present, where he speaks with the mysterious traveler from their home city state (either Y'shtola, Thancred or Yda and Papalymo), who warns that the Empire cannot be defeated in their current state, the player must find something much greater if he has any hope of defeating the Garleans and freeing Eorzea from their menace.

Fighting against the Garleans, the player encounters another Imperial Legatus named Nael van Darnus who sees the invasion to be for the greater good. However, as the player fights against the Primals themselves whose demise was Nael’s wish, his plan is revealed to exceed the intent of the Garlean Empire by Nael's desire to purge Eorzea of its impurities with Dalamud. Though Gaius helps the player to stop the insane general, Nael becomes infused with Dalmund's power and resolves to plunge the world in the Seventh Umbral Era.

Not long after, the companies are able to track down Nael van Darnus's location; the Legatus is seen wandering near the Allagan Ruins in Camp Glory. An attack group is quickly assembled and sent to the region, only to find a patch of floating islands emanating a light similar to the one previously seem on Castrum Novum, the Rivenroad. From the Rivenroad, Nael oversees fiery rocks raining down from Dalamud.
Without any other alternatives to reach the Legatus's, the companies seek Cid for an airship. After a few preparations, Cid offers his personal airship, the Enterprise. However, the airship can only carry a small number of passengers, and as such, only a single group of adventurers are able to fly towards the floating islands for the final confrontation against the Legatus.

After a fierce battle, the party seemingly succeeds in defeating the legatus. However, he stands up and is bathed by Dalamud's light, losing what was left of his mind and becoming a being of pure hatred. The battle starts once again, and the party finally defeats Nael. Following his defeat, the magic glyphs keeping the Rivenroad floating are deactivated, and the island starts falling apart. The group has no means to escape, but soon after Cid Garlond appears and rescues everyone, bringing the group to safety.
The Grand companies celebrate victory with a reunion in Gridania, as Cid assures everyone that Dalamud will no longer crash on Eorzea; however the player wonders if that's true, as there is still a sense of dread about Dalamud.

Louisoix advises the player to take a pilgrimage of the Twelve, on which they encounters Gaius, who warns the player of a VIIth Legion, who still remain loyal to Darnus, despite being seemingly defeated at Rivenroad. He also tells the player of the Legion's movements in Mor Dhona, who are gathering in Castrum Novum for the invasion of Eorzea. With that, he disappears, reminding the player to leave him something worth conquering. Armed with this knowledge, the player alerts Louisoix who passes the information along to the heads of the Alliance.

With Dalamud drawing ever closer, the very nature of Eorzea begins to rapidly change. A mysterious being known as Atomos appears at Aetherial Crystals, spawning powerful monsters from the void, leaving crystals filled with aether. Things take a dramatic turn for the worse when monsters, imperial legionaries and Darnus himself begin to attack the City-States directly. Realizing the final battle is near, the Alliance prepare themselves by calling upon all of those who are still able to bear arms. The Eorzean Alliance will face the Garlean Empire's lead invading force at Carteneau Flats in Mor Dhona, the predicted point of impact for Dalamud.

The battle begins, furious and bloody, with Dalamud just overhead. Neither side steps back from their conviction, until a roar tears across the sky, and a massive pillar falls from Dalamud. The Alliances stares in awe. The final phase of Darnus' Meteor Project is complete, and as the pieces of Dalamud begin to shower Eorzea with flames, they realize the worst is yet to come. From within Dalamud, the elder Primal, Bahamut awakens from his slumber, and begins to bathe the world in fire.

All would seem lost, as a few adventurers (the player & company) watch the world burn around them. A seemingly indifferent meteor approaches, until they are saved by Louisoix, who is attempting to create a shield. Unfortunately, the shield cannot withstand Bahamut, who menacingly approaches Louisoix. In a last ditch effort, he attempts to recreate Dalamud to imprison Bahamut with the power of the Twelve. All is for naught, however, as Bahamut simply breaks free and continues his reign of fire. With his dying breath, the Archon calls upon the power of Althyk to transport the adventurers into a rift of time and space, where they will be untouched by Bahamut's fury, until the time is safe for them to begin their struggle anew.

Seventh Umbral Era Video (Awesome Vid :3)
FFXIV 1.0 - The End


There is a website with a collection of FFXIV 1.0 videos/cutscenes. I am not sure if all of them are included, but there are quite a few on the website if you are interested in viewing those. :)

Final Fantasy XIV 1.0 Cutscene Collection