The decline began in the 1880's as industrialization increased.
Jerusalem is your answer
Jews: Jerusalem was the capitol of ancient Israel, and was also home to the ruins of the Temple built by King Solomon during the Golden Age of Israel.
Christians: Christians typically trace their roots back to Judaism, as they also believe in the old testement. In fact, the church was started in the area of Judah, which was close to the original Temple site.
Muslims: Muslims believed that Jerusalem was the home to the prophets of Islam, and the Qur'an also mentions Jerusalem many times, making the city important.
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They organized their lives by expanding their trade routes by spreading further in the desert also become major carriers of good.
B. He conquered the last of the Song Dynasty and brought China under Mongol rule.
Explanation:
Kublai Khan is one of the best known Mongol rulers, both for good and for bad. He was the grandson of Genghis Khan, and unlike his grandfather and father, he ruled in a manner that promoted tolerance among the different groups of people. One of the things by which Kublai Khan is best known is that he was the first Mongol to conquer and rule all of China.
Kublai Khan managed to conquer the last independent Chinese state, the Song Dynasty, incorporated it into the Mongol Empire, and formed the Yuan Dynasty. While this was seen as a great success and promised a long lasting and powerful empire, Kublai Khan also made some mistakes (mostly military ones) that actually started off the decline of the empire.
The correct answer is World War II
Following World War II, the United Nations were found with a goal of preventing such monstrosities in the future.