why was the shang dynasty overthrowed and who overthrew it?

M, the last king of Shang Dynasty was King Zhou. When he ascendeded to the throne, he acted like an elightened ruler. He sent his troops to fight other tribes in the east and south. His purpose was to expand Shang's territory. After the victory, he became arrogant and self-coneited. He indulged in excessive drinking and played with beautiful ladies. Meanwhile, he taxed his people heavily to get enough money to continue his extravagant life. Thus, social contradictions became severe.

At the same time, Ji Fa succeeded his father Ji Chang to be the leader of Zhou Tribe. He put capable people in the important positions and helped his people to develop agriculture. Suddenly, Zhou Tribe became stronger than other states.

In 1046, Ji Fa brought around 50000 soldiers to crusade against King Zhou. King Zhou didn't prepare for the war very well. You know, his elite army was deployed at the border and was busy with the wars against other states. Therefore, King Zhou armed around 170000 slaves to fight Ji Fa and his army. Unfortunately, he lost the war and burnt himself in his palace finally.