Mesopotamian trade relations extended far to the north and south. The silver that the citizens of Ur used for their currency may have come from Anatolia, or modern-day Turkey. Ur was the most southerly of the major urban centers, and its position on the gulf allowed it to control maritime trade to points south. Dilmun was a maritime trading nation that imported goods like copper and perhaps wood from points in Africa and the Arabian peninsula, like Magan (possibly modern day Oman) when copper foundries from the third millennium have been excavated. The Ur traders may have sailed as far as the Indus valley, in modern-day Pakistan for precious stones. Perhaps these economic relations account for the early development of financial contracts and currency in the Indus civilization as well.