http://www.jpost.com/Israel/Article.aspx?id=181135
The tiny fragment is only 2 cm. by 2.8 cm. in surface area and 1 cm. thick and appears to have once been part of a larger tablet. Researchers say the ancient fragment testifies to Jerusalem’s importance as a major city late in the Bronze Age, long before it was conquered by King David.
It is not as if we had no evidence of a city in that location in the MBA. There is correspondence between its king and the Egyptian court in the Amarna collection.