Everyone has heard the categories of Muslim and non-Muslim or Kafir, but few have heard of Islam’s third social category, the dhimmi. Under Islamic rule, Christians and Jews could convert to Islam and become full citizens. If they chose to remain a Christian or Jew, they could pay a special tax, called the jizyah and become a semi-slave called a dhimmi. In addition to the semi-slave status, a dhimmi is humiliated and subjugated.
The first dhimmis were the Jews of Khaybar. After their defeat by Mohammed, they lost their land and possessions and had to live under Sharia law. The Jews continued to farm the land, but had to give Mohammed half of their income, the jizyah tax.
It was the dhimmi status which caused the collapse of Christianity in places like the Middle East and Turkey.