You are right Shantipriya. Among three great kings of Licchavi era, king Anshu Verma was a khas/ thakuri (Verma means a chhetri) and not from the regular lichhavi dyansty. And the newars are really rooted to the Lichhavi period not the malla period. The surnames like shrestha, rajbhandari, amatya etc hail from that period but not malla. The official language in the licchavi kingdom was sanskrit. For instance, the cheif of army was called " Mahabaladhakshya", the villages were called "gram" etc. The common language of communication was Khas. They were in close contact with khas kings of the west. For instance, the kasthamandap in basantapur was built by Jumli khas king Malaya Bam (=Malaya Verma). Even one of the ktm malla king was a grand son of great khas king Prithvi mall of Jumla. Since the throne of Nepal khaldo remained unclaimed because one of Malla king in ktm had no son, they brought a Jumli prince and made king of ktm. So, the debate over newar and khas is pointless. Khas were in khaldo from time immemorial, even before the mallas migrated  to nepal khaldo from northern india.