Vishwa Rath was a king of the Kaushika lineage, one with many generations of kings. 
He loved to hunt and usually a large army would accompany him on these hunts. 

It was on one of these hunts that he realized that he was in the vicinity of the Ashram of the great Guru Vashisht. 

It is said that with these blessings of Guru Vashisht, Vishwamitra’s consciousness expanded and the Mahagayatri Mantra was realized by him.