Premise: Originally known as Edo (meaning estuary ), Tokyo was just a sleepy little village surrounded by marshland on the broad Kanto plain until the end of the 16th century, when Tokugawa Ieyasu moved here and made it the center of his vast domains.

Hypothesis: Tokyo was once a small village called Edo, but rapidly grew in the 16th century when Tokugawa moved there.
Relation: entailment