Long distances and the severe Arabian climate had kept these civilizations from invading the peninsula. This isolation, however, was not absolute, as trade brought some outside ideas and practices to the Arab civilization.
Over centuries, Islamic scholars created a code of law called the shari'ah. Shari'ah is based on the Quran. According to shari'ah, Muslims may not gamble, eat pork, or drink alcoholic beverages.
The Shia and the Sunni agreed on the major principles of Islam. They both believed that there was only one God. They also believed in the Quran as Islam's holy book and the Five Pillars of Islam.
a street of small shops, especially in the Middle East
Another important feature of every Muslim city was the bazaar, or marketplace. Like shopping malls today, bazaars were full of shops and stalls where goods were sold.
instrument used to calculate positions of celestial bodies
Muslim astronomers improved the Greek astrolabe. Sailors used this tool to determine their location at sea. Muslim scientists used the astrolabe to measure the distance around the Earth.