In 209 BC, three years before the founding of Han China, the Xiongnu were brought together in a powerful confederation under a new chanyu, Modu Chanyu. This new political unity transformed them into a more formidable state by enabling the formation of larger armies and the ability to exercise better strategic coordination. The Xiongnu adopted many of the Chinese agriculture techniques such as slaves for heavy labor and lived in Chinese-style homes. The reason for creating the confederation remains unclear. Suggestions include the need for a stronger state to deal with the Qin unification of China that had resulted in a loss of the Ordos region at the hands of Meng Tian or the political crisis that overtook the Xiongnu in 215 BC when Qin armies evicted them from their pastures on the Yellow River.