The government exerted control on all exports. The export of yerba mate and valuable wood products maintained the balance of trade between Paraguay and the outside world. The Paraguayan government was extremely protectionist, never accepted loans from abroad and levied high tariffs against imported foreign products. This protectionism made the society self-sufficient, and it also avoided the debt suffered by Argentina and Brazil. Slavery existed in Paraguay, although not in great numbers, until 1844, when it was legally abolished in the new constitution.