The Vedas are set in the framework of the geography of the Indian subcontinent. This is clearly obvious through the innumerable references to geographical features.
For example, the River Hymn (Nadi Suktam) RV 10.75 lists all the major rivers of northern India in precise order from east to west.
इमं मे गङ्गे यमुने सरस्वति शुतुद्रि स्तोमं सचता ...
king Vṛṣaṇaśva is mentioned in Rig-Veda mandala 1- Sukta 51-Mantra 13.Indra once took birth as a daughter of Vṛṣaṇaśva and her name was Mena.
As you requested , below are the three translations of the mantra where the king Vṛṣaṇaśva is mentioned in Rig-Veda.
Translation By H.H.Wilson
अददा अर्भां महते वचस्यवे कक्षीवते वृचयामिन्द्र सुन्वते | मेनाभवो