Conversation so far:
How were the Sinhalese kingdoms formed?
Sinhalese kingoms were formed by Prince Vijaya and his 700 followers. They left Suppāraka, landed on the island and founded the Kingdom of Tambapanni.

Question: Who or what are the Tambapanni?
Self-contained rewrite: Who or what are the Tambapanni in relation to the Sinhalese people and their kingdom?