500
The Man who wrote this in his travels:
"First there is the salt, which brings in a great revenue. For its produces every year, in round numbers, a vast sum of money! (This province, you see, adjoins the ocean, on the shores of which are many lagoons or salt marshes, in which the sea-water dries up during the summer time; and thence they extract such a quantity of salt as suffices for the supply of five of the kingdoms of Manzi (South China) besides this one.) "
What is Marco Polo?