In an alternate timeline…

3000BP - The Three Tribes Period. A time of frequent conflict between the rival warlords of the Earth Ponies, Pegasi and Unicorns for control of the fertile Equestrian river valley. Ends with the tribes forming a coalition in response to incursions from northern Wendigo horse nomads (1000000 ponies die).
2800BP - A local official of the Earth Pony tribe named Pu Ding seizes power in a coup and establishes the Pon Dynasty.
2500BP - A succession crisis, exacerbated by scheming geldings in the imperial court, destabilises the empire. A barbarian chieftain named Di Shukord takes advantage of the chaos and invades Equestria (4500000 ponies die), conquering the Pon Dynasty and proclaiming himself emperor of the new Di Dynasty. The new emperor is cruel and arbitrary. 50000 ponies die in the construction of his lavish palaces and large scale displacement of farmers leads to food shortages (up to 10000000 ponies die in the famine).
2000BP - A revolt led by the sisters Tian and Lu Na topples the Di Dynasty (2500000 ponies die) and the Sun Dynasty is established in its place. Widely considered a golden age, the early Sun period was mostly peaceful and prosperous, despite the loss of one of the emprire’s nothern provinces to a rebellious warlord.
1000BP - Lu Na, despite being nominally co-empress, is politically sidelined by her more influential sister. She launches a rebellion, razing the imperial capital to the ground and proclaiming herself sole empress of the short-lived Mun Dynasty (3000000 ponies die). After a bloody conflict, Tian finally puts down the rebellion and Lu Na is exiled from Equestria. Empress Tian establishes a new capital in the empire’s highly defensible mountainous heartland, and rules alone.