Uśīrabīja is a sacred mountain named in the Vana Parva of the Mahābhārata. It belongs to the northern holy places that the Pāṇḍavas passed on their tīrtha yātrā (pilgrimage to holy places). Lomaśa names it in the list of northern mountains and sacred places as he guides Yudhishṭhira and his brothers through the lands of the Himālaya.

Where it lies

Uśīrabīja lies in the northern mountain region of the Himālaya. It stands near the tīrthas on the road that leads from Kāmyakavana northward, through the sacred river valleys, toward Gandhamādana. The word uśīra means a sweet-smelling grass (vetiver). (Mahābhārata, Vana Parva)

Sources

Mahābhārata, Vana Parva (the chapter is not given)