The dragon sails west
After six years of learning to rule in a foreign country, Daenerys Targaryen finally turns her fleet toward Westeros with dragons overhead, the Dothraki behind her, and the Greyjoy and Martell and Tyrell alliances in hand. Everything the story has been building toward on two continents is finally in the same sea.
The fuller tale
It took Daenerys Targaryen six years to get from a Dothraki wedding to a fleet pointed at Westeros, and almost all of that time was spent on the thing the songs leave out: what happens after you win.
She had broken three slave cities in a year and then discovered that a city is not a thing you can free, only a thing you can take responsibility for. Meereen gave her a masked insurgency, an economy with its one leg cut off, a marriage of state she did not want, a fighting pit she had promised to keep closed, and several years of learning that her instinct ÔÇö burn the obstacle ÔÇö made every problem worse in ways that took months to show up.
What finally freed her was going backwards. She was taken by a khalasar, walked into a temple fire in front of every khal in the Dothraki sea, walked out of it, and left with a horde. With the Greyjoy fleet, the Dornish, the Tyrells and three grown dragons, she turned west at last.
The two halves of the story
For five years the chronicle has been two books that do not touch: a war of succession in Westeros, and a woman learning to rule on another continent. Everything from here is the two of them arriving in the same room.
She comes with the largest force anyone has assembled since the Conquest and with a set of assumptions formed entirely in Essos, where she was liberating cities from slavers. Westeros is not that, and nobody there is waiting for her.
Elsewhere in the wiki
 See the world as it stood in 302 AC What became of it  if an ending is written, it is here. Spoilers.
The chronicle records no ending here ÔÇö or none the maesters have set down.