Caliphates

Answer 1

The Muslim empire treated conquered people who converted to Islam as equals,those who didn't became 2nd class citizens.

Answer 2 - Non-Muslim Answer

In the Middle Ages, Muslims treated non-Muslims in a way that was superior to contemporaneous civilizations and introduced the concept of religious tolerance (as opposed to Europe which was practicing the exact opposite at the time). However, it is nothing close to equality or Rights. An important thing to note is that the concept of Rights comes out the Enlightenment. Prior to this point, there was a system of privilege wherein the Ruler would provide privileges (out of the kindness of his heart) to a certain group of people to do acts. A person did not have the "right" to anything and this was the mentality worldwide.

The Pact of Omar was a document of submission signed by the Caliph Omar and defeated Christians and Jews during one of Omar's Wars. While the factual accuracy of that story may be doubted, there is no doubt that the Pact of Omar formed the basis for the treatment of non-Muslims in the conquered territories. The Pact of Omar set out a number of regulations that will be described in this answer.

The Dhimmi, or non-Muslim under Muslim occupation was required by the Pact of Omar to pay a number of taxes that were connected with his Dhimmi status. The most famous was the jizya, which was a tax that Dhimmi had to pay for Muslims for the right to not be killed where they stood for not acknowledging Mohammed's Prophecy; it was a form of humiliation. Additional taxes included the kharaj, which was a tax on non-Muslim* land-holdings in the Muslim World. The kharaj was so untenable that most Dhimmi were forced to live in the cities where the tax would not be applicable. There was also inequality concerning the justice system. On paper, a Christian or Jew could testify against a Muslim, but in reality, such testimony was not acceptable and the attempt to defame a Muslim would receive retribution. Christians and Jews were not allowed to build new houses of worship, restore old houses of worship, proselytize in any way (this included religious debate or dialogue), or allow wine or pigs to be shown in public.

Polytheists were forced to convert to Islam with some rare exceptions (such as the Hindus in India). Zoroastrianism was the majority faith in Iran until Islam almost completely extinguished it, both by sword, economic inequality, and brutal repression of Zoroastrian customs (unless they could be Islamicized like Nourouz).

This system of inequality between Muslims and non-Muslims persisted up to the colonial period, when it reversed. As a result of colonization, the segregated Dhimmi System gave way to a new, modern bureaucratic system where Europeans were the dominant class and natives, regardless of their religion were second-class, unless they became part of the bureaucracy. To do this, a person would require an education in order to become literate and be able to successfully perform functions in the Arab World. As Jews and Christians sought education, they were able to ascend the hierarchy and become relatively powerful compared to the Muslim majority. When the Islamic World became independent, only the Lebanese Christians were able to maintain this dominant position (and only until the Lebanese Civil War of 1975-1991). In other countries, the end of colonization saw a brief rise in Anti-Semitism followed by a mass exodus of Jews from majority-Muslim countries for Israel, UK, France, the United States and Canada. Those Jews and Christians who remained garnered a more equal status than anything that they had previously had under Muslim leadership, but still are unequal in terms of their inability to proselytize, the unofficial "requirement" to avoid offending Islam in public, and the need to seek the authority of high government officials to build new houses of worship or to repair existing ones.

*Although Muslims also had to pay the kharaj in theory, in practice the tax rate for kharaj on Muslims was slight compared to the amount required by the Dhimmi peoples.