The vertical trade is trade that essentially appears between people living in different elevations. In the Andean region, the vertical trade has a long history, and it has been performed between the people living in the higher parts of the Andes, and the people living in the valleys and coastal regions east and west of the Andes.
This type of trade helped the people to be able to survive and develop in both of those environments, as the people living high in the mountains were producing certain things, and the people living in the lowlands were producing certain things that both of them needed in their daily lives. Because they collaborated, they were able to create societies in totally different environments and thrive for centuries.