The Denomination of Origin of Tejo has six sub-regions (Almeirim, Cartaxo, Chamusca, Coruche, Santarém and Tomar). The soils vary according to their proximity to the sea. Marshlands are very fertile areas located by the river. Tejo’s floods tend to completely immerse the fields.
Tejo has been famous for producing large quantities of wine that would supply restaurants and taverns in Lisbon. Its large agricultural holdings would seek to obtain the maximum profit from the vines and produce low quality wine to be sold in bulk. In the last 15 years, the region underwent significant changes, not only in the fields but also in the wineries. Many vines were transferred from the fields near the sea to the ones in the interior. This lowered production, but increased quality.