Modu ruled from 209 BCE to 174 BCE. He was a military leader under his father Touman, and later Chanyu of the Xiongnu Empire, situated in modern-day Mongolia. He secured the throne and established a powerful Xiongnu Empire by successfully unifying the tribes of the Mongolian-Manchurian grassland in response to the loss of Xiongnu pasture lands to invading Qin forces commanded by Meng Tian in 215 BCE. While Modu rode and then furthered the wave of militarization and effectively centralized Xiongnu power, the Qin quickly fell into disarray with the death of the first emperor in 210, leaving Modu a free hand to expand his Xiongnu Empire into one of the largest of his time. The eastern border stretched as far as the Liao River, the western borders of the empire reached the Pamir Mountains, whilst the northern border reached Lake Baikal.