The post-Vedic period of the Second Urbanisation saw a decline of Brahmanism. At the end of the Vedic period, the meaning of the words of the Vedas had become obscure, and was perceived as "a fixed sequence of sounds" with a magical power, "means to an end." With the growth of cities, which threatened the income and patronage of the rural Brahmins; the rise of Buddhism; and the Indian campaign of Alexander the Great (327-325 BCE), the expansion of the Mauryan Empire (322-185 BCE) with its embrace of Buddhism, and the Saka invasions and rule of northwestern India (2nd c. BC – 4th c. CE), Brahmanism faced a grave threat to its existence. In some later texts, Northwest-India (which earlier texts consider as part of "Aryavarta") is even seen as "impure", probably due to invasions. The Karnaparva 43.5-8 states that those who live on the Sindhu and the five rivers of the Punjab are impure and dharmabahya.