What was the taxation system in …

Islamic taxes are taxes sanctioned by Islamic law.

Islamic taxes include:

i. zakat - one of the five pillars of Islam. Only imposed on Muslims, it is generally described as a 2.5% tax on savings to be donated to the Muslim poor and needy. It was a tax collected by the Islamic state.
ii. jizya - a per capita yearly tax historically levied by Islamic states on certain non-Muslim subjects—dhimmis—permanently residing in Muslim lands under Islamic law, the tax excluded the poor, women, children and the elderly.
iii. kharaj - a land tax initially imposed only on non-Muslims but soon after mandated for Muslims as well.
iv. ushr - a 10% tax on the harvests of irrigated land and 10% tax on harvest from rain-watered land and 5% on Land dependent on well water. The term has also been used for a 10% tax on merchandise imported from states that taxed the Muslims on their products. Caliph `Umar ibn Al-Khattāb was the first Muslim ruler to levy ushr