Timna in Yemen should not be confused with the Timna in the Negev. When Pliney the Elder made his comment about the distance that the Incense Route covered, he used Timna as the starting point, and Gaza as the end point of the route. It seems that much of the Incense from Southern Arabia was gathered and transported to the markets at Timna. It was here that the camel caravans gathered to purchase Incense and transport it to the Mediterranean Sea far to the north.
An American excavation of Timna took place in the 1950s. More information about Timna and South Yemen can be found on this web page: Southern Arabia