Revolts against Muhammad bin Tughlaq began in 1327, continued over his reign, and over time the geographical reach of the Sultanate shrunk. The Vijayanagara Empire originated in southern India as a direct response to attacks from the Delhi Sultanate., and liberated south India from the Delhi Sultanate's rule. In the 1330s, Muhammad bin Tughlaq ordered an invasion of China, sending part of his forces over the Himalayas. However, they were defeated by the Hindu kingdom of Kangra. Few survived the journey, and they were executed upon their return for failing. During his reign, state revenues collapsed from his policies such as the base metal coins from 1329–1332. To cover state expenses, he sharply raised taxes. Those who failed to pay taxes were hunted and executed. Famines, widespread poverty, and rebellion grew across the kingdom. In 1338 his own nephew rebelled in Malwa, whom he attacked, caught, and flayed alive. By 1339, the eastern regions under local Muslim governors and southern parts led by Hindu kings had revolted and declared independence from the Delhi Sultanate. Muhammad bin Tughlaq did not have the resources or support to respond to the shrinking kingdom. The historian Walford chronicled Delhi and most of India faced severe famines during Muhammad bin Tughlaq's rule in the years after the base metal coin experiment. By 1347, the Bahmani Sultanate had become an independent and competing Muslim kingdom in Deccan region of South Asia.