Mahabharata 1.89.36

1.89.36

teṣāṃ nivasatāṃ tatra sahasraṃ parivatsarān |
athābhyagacchadbharatānvasiṣṭho bhagavānṛṣiḥ || 36 ||

And the Panchalas setting out to invade the whole earth with their four kinds of troops soon brought the whole earth under their sway. And with their ten Akshauhinis the king of the Panchalas defeated the Bharata prince. Samvarana then with his wife and ministers, sons and relatives, fled in fear, and took shelter in the forest on the banks of the Sindhu extending to the foot of the mountains. There the Bharatas lived for a full thousand years, within their fort. And after they had lived there a thousand years, one day the illustrious Rishi Vasishtha approached the exiled Bharatas, who, on going out, saluted the Rishi and worshipped him by the offer of Arghya.