im read that need mods are open for sugestion and historical research, im happy to help :
{Islam Based}
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-Simmilar to Christianity, it's main City is Baghdad, and has a religous leader as well. It does most of the same stuff as Christanity, much is more of warriors and does not require churches or in their case temples to be in good terms with them, as they only have few temples, instead to have good relation you must instead do religious missions, which give you double relation if completed, and you get missions not at will but by messages you get very so often.
this will be interesting, for more historical accurate, in Islam we call our place for prayer as "masjid" not temple, and also not a mosque, mosque its not an accurate words it base on war insults (many muslim still recognize this as an insults acording to the etimology of this word), although we dont have any religious institution and order (like vatican etc) but yes we are forming battle formation, tactic, event politic in masjid at that time. We dont have any religious leader, all man recognize equal as the practicer, but we have a leader that we recognize as the leader of all muslim arround the world, it call Caliph.
There is a different between Islamic Caliphate system or we can call it Khilafah Islam wich is totaly different with modern mid-east monarch for example : Arab Saudi (Ibn Saud monarch). The ruler not being elect by blood relation (unlike monarchy or feudalism) but by asyura, or discussion, there is some kind of election who will be chosen to be a caliph or populary to be chosen as a Amirul Mukmin(in) (mean : The Leader Of The Belivers)-this name being introduce by Umar Ibn Khatab, and since then all the Islamic Caliph call their leader by this name. For more information u can check a biography of Umar Ibn Khatab ra. or u can also check Umar Ibn Abdul Aziz ra. story or biography, they are two well known caliph who are being respect by the muslim for their political and state policy. Also the terms of Imam or ulama is not kind of institution terms that legitimately granted, it being given by the peoples because your knowledge (especialy about Tauhid-oneness of God, or fiqh-knowledge about religion law or syariah etc) on religion and for your works and good deeds, its a name of honor by the mean that you are worth to be a good example and right person to ask on religious matter.
And we have lots of masjid, but they just modest place to worship, not one with a sophiscated architecture. Except in the Ottoman area, there are many luxurious and high decorated masjid in Andalus or Cordoba. Event its not a good things to do, because the teaching of modesty (zuhud) are one of important teaching in Islam, not only in wealth, event in simple every day life like food and clothes. Umar Ibn Abdul Aziz biography is good to be start, because its short, simple and can give u a brief understanding about political atmosphere in Islam. ANd in Umar Ibn Khatab there are lots of things to read, event a detail on how the caliph relation with peoples of the books (christian and jews) and Umar being love by the Jews and christian because of his fair judgement on trade and religious right, and he have a unique political observation as periodictly go to town pretending as a citizen and asking a villager how things going under his order, how trade, how life, and other things. If u need refrence or interest adding Islamic detail at your mods contact me.