I want to know the answer to the following question:
When did the Kamakura Bakufu Shogunate open?
All the background I'm provided with is that "After the Genpei war of the late 12th century, a clan leader Minamoto no Yoritomo obtained the right to appoint shugo and jito, and was allowed to organize soldiers and police, and to collect a certain amount of tax.". Is that enough to answer the question?