Sumida River
The clan originated in Chichibu in Musashi Province (now Saitama Prefecture). In the late 12th century, Edo Shigetsugu moved south and fortified the little hill at Edo, located where the Sumida River enters Tokyo Bay. This area later became the Honmaru and Ninomaru portions of Edo Castle. There, the Edo grew in military strength under the second patriarch, Edo Shigenaga.