Trade with Ming China via Manila served a major source of revenue for the Spanish Empire and as a fundamental source of income for Spanish colonists in the Philippine Islands. Galleons used for the trade between East and West were crafted by Filipino artisans. Until 1593, two or more ships would set sail annually from each port. The Manila trade became so lucrative that Seville merchants petitioned king Philip II of Spain to protect the monopoly of the Casa de Contratación based in Seville. This led to the passing of a decree in 1593 that set a limit of two ships sailing each year from either port, with one kept in reserve in Acapulco and one in Manila. An "armada", or armed escort of galleons, was also approved. Due to official attempts at controlling the galleon trade, contraband and understating of ships' cargoes became widespread.