Conversation so far:
How early were the first Sinhalese kingdoms mentioned?
Early recorded history of the Sinhalese is chronicled in two documents, the Mahavamsa, written in Pāli around the 4th century CE.
Was Vijaya a king in Sri Lanka?
Prince Vijaya was the traditional first Sinhalese king of Sri Lanka
What year was Vijaya's reign in Sri Lanka?
His reign is traditionally dated to 543–505 BCE.
Were there any other Sri Lankan kings mentioned in the article of the Pre Anuradhapura period?
Upatissa, the Chief government minister or prime minister and leading chief among the Sinhalese became regent and acted as regent for a year.

Question: How long did the kingdoms last?
Self-contained rewrite: How long did the Sinhalese kingdoms last?