King Aamraja of Gwalior fell in love with a very beautiful jain girl so he married her. After some days Acharya Bappbhatta Suri came in the Gwalior city. The queen desired to see the Acharya so King with whole family went to the Acharya's Upashraya (the place where jain muni stay) and heard his lecture. King was so impressed that he followed the Jainism. His son became the in charge of the states Kothar (treasure) so he and his family were known as Kosthagar or Rajkosthagar.

Tolashah and Karmashah were the famous personalities of this gotra.

Their Kuldevi is Shri Beeshath Mataji, Jodhpur.