In past decades, Bolivia's rubber industry was hamstrung by a long stretch of unnavigable rapids, which prevented the shipment of latex down the Amazon. To solve this conundrum, Bolivia offered its Acre Territory if Brazil agreed to fund a railroad which bypassed the rapids. The treaty was signed in 1903, and work commenced soon after. Porto Velho was established at its end to move latex from traincars onto cargo ships, and until recently, this trade represented virtually all of Rondônia's economy. But with the recent discovery of large tin deposits and rapidly rising demand for wood and beef, the territory is rapidly diversifying, and Porto Velho is diversifying in tandem. This is not without cost, as indigenous communities which had remained intact since before the voyages of Columbus now find themselves increasingly threatened by Brazilian settlers and their diseases.