Simplify the following text for a Grade 9 native English-speaking person.
Original: Edo , literally : bay-entrance , `` estuary '' , pronounced , also romanized as Yedo or Yeddo , is the former name of the Japanese capital Tokyo , and was the seat of power for the Tokugawa shogunate which ruled Japan from 1603 to 1868 .
Simplified: Edo is the former name of the Japanese capital Tokyo , and was the seat of power for the Tokugawa shogunate which ruled Japan from 1603 to 1868 .