Nalapani, Kalopani, Happy2009 You guys are all right to some extent ...

Basnet and Basnyat are of different gotra.. (Originally)..  Basnyat are Sirupali and Basnet are Khaptadi.. Basnet origins in Khaptad where as Basnyat main roots goes all the way to Rajisthaan, and migrated with the shahs to Gorkha..

Modern days for ease ppl started writing Basnet instead of Basnyat..

The place you are talking about in Asan is called Tilanga.. It has been said that after Prithvi Narayn Shah won over KTM, and he decided KTM to be the new capital of Nepal. He placed his main ppl around different sector of KTM .. Basnyat got the Tilangaa house in Asan..

The palace we now know as Narayanhiti was built by Basnyat as well.. This was the house of Kaji Dhaulak Singh Basnyat..  Most of the Basnet / Basnyat that you see from Mahankal thaan all the way to Tilangaa house in Asan are Sirupali Basnyat..

Hope this helps...

Sna - Basnet / Basnyat are not newars..