Mahabharata Adi Parva Chapter 141:2

Mahabharata Adi Parva (Sambhava Parva)

Mahabharata Adi Parva Chapter 141:2 And the king of the Yavanas himself whom the powerful Pandu even had failed to bring under subjection was brought by Arjuna under control. Then again Vipula, the king of the Sauviras, endued with great prowess, who had always shown a disregard for the Kurus, was made by the intelligent Arjuna to feel the edge of his power. And Arjuna also repressed by means of his arrows (the pride of) king Sumitra of Sauvira, also known by the name of Dattamitra who had resolutely sought an encounter with him. The third of the Pandava princes, assisted by Bhima, on only a single car subjugated all the kings of the East backed by ten thousand cars. In the same way, having conquered on a single car the whole of the south, Dhananjaya sent unto the kingdom of the Kurus a large booty. "Thus did those foremost of men, the illustrious Pandavas, conquering the territories of other kings, extend the limits of their own kingdom. But beholding the great prowess and strength of those mighty bowmen, king Dhritarashtra's sentiments towards the Pandavas became suddenly poisoned, and from that day the monarch became so anxious that he could hardly sleep.'"