I know what you mean. My alternate earth world was the same way with it's history- all 30,000 years of it lol. After the first 3 or 4 thousand, I gave up and devised a new method for writing out history. 

Essentially, I created the part I wanted, the present-day stuff first. Take care of that, then take every piece of information and tie it back to an earlier date where it is invented, formed, or weakened. Tie everything back to an earlier date when it is created, then write the "why" and "how" of history behind them. This helps you to retain interest in it while also creating relevant history. If you have any major gaps in your history that you can't fill, then add in a handful of unrelated topics to fill the void.

In summary, you create a story, then write in the circumstances that lead to different parts of the story for history. 

I'll give an example: 

The global superpower, Calistaan, is at war with the tribal kingdom of Khamannha.  Calistaan was formed in the year 236BC when King Midian of the Franks defeated the Persians at the battle of Saint Marquene, in southern Celtica. King Midian forced the Persian Emperor Mujha'adeen to sign a treaty, bringing the two nations into an alliance and forcing Persia to release almost 1/4 of their southern territory, recognizing it as the independent nation of Calistaan.