Islamic Conquest of Jerusalem
After the bitter battles they had endured with the Persians, in which hundreds of lives were lost, the Christians of Jerusalem felt that they had earned possession of the Holy City with their life’s blood. But less than ten years after the battles between Byzantium and Persia at last came to an end, Caliph Umar’s armies arrived at the gates of Jerusalem. They had already subjugated much of the country, and victory over the Holy City therefore seemed assured. Patriarch Heraklios fled the country, taking the True Cross from Jerusalem with him.
When at last the Greek Orthodox Patriarch Sophronius of Jerusalem was forced to surrender in 638 A.D., Umar is believed to have traveled to Jerusalem personally in order to receive the surrender. Umar had become the second caliph following the death of Abu Bakr, making him one of the earliest successors of Mohammed himself. His procession into the city was a humble one: the caliph was clad in simple attire, leading a camel. His conquest of Jerusalem, once the city had surrendered, was marked by its lack of further killing and destruction. The Christian holy sites were one and all left intact.
When Umar asked Sophronius to guide him to the city’s holy places, the patriarch took the caliph to the Church of the Holy Sepulchre. Famously, Umar refrained from praying within the church itself, as that would have transformed the church into a Muslim holy site. Instead Umar prayed outside in the streets of Jerusalem.
But the caliph was most curious to see the Temple of Solomon, of fabled magnificence. He was horrified to discover that the Temple was in ruins, and the Temple Mount itself had become a rubbish heap in which the city garbage was regularly dumped.
Building on the Temple Mount
It was at this moment that Temple Mount’s identity as a site holy to Islam began to take shape. Umar commanded his men to clear the rubbish from the platform. He then had a rough-hewn wooden mosque built at the southern end of the platform, the first incarnation of what is known today as Al Aqsa.
The Temple Mount was at that time the logical place for a mosque: It had been the site of the Jews’ Holy Temple, which the Muslims revered, and was not sacred to Christianity. The repercussions of Umar’s decision to build a mosque on the holiest site to Judaism would not yet be felt in his lifetime, nor for many years to come. Does this justify Israel's ownership? source: http://www.gojerusalem.com/article/260/Islamic-Conquest-of-Jerusalem/

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