by what process did Wendi establish the Sui dynasty?

When Yuwen Chan became the emperor of Northern Zhou, he appointed Yang Jian as prime minister. However, Yuwen Chan was just a seven years old child. He couldn't take care of political affairs. Therefore, Yang Jian actually became the one who actually controlled the imperial court. He inveigled five princes to return to Chang'an and then killed them all. Meanwhile, he sent Wei Xiaokuan to defeat Yuchi Jiong so that he cleared all his political enemies.

In 581, Yuwen Chan abdicated and handed over the throne to Yang Jian. Yang pretended to decline three times. Eventually, he came to the palace and became the emperor. He established Sui Dynasty and was named Emperor Wendi.