 During the 19th century Peru established a virtual international monopoly in the trade of guano, another fertilizer, and since the 1840s income from this source had financed the Peruvian Guano Era.By the 1860s these revenues were in decline, as deteriorating quality led to a reduction of exports.Alongside this trend, nitrate exports from the Peruvian province of Tarapacá grew, and became an important competitor to guano in the international market.