This paper is aimed to recognize climatic and environmental conditions prevailing during the main occupation of La Bolsa 1 archaeological site (ca. 200 BC-900 AD) through palynological analysis of archaeological soil samples taken from agricultural structures. During the period studied, the vegetal communities which had developed in the Tafi valley suffered local variations, as a consequence of alternating dry and humid periods, the last ones possibly coincided with the introduction of agriculture in the region. Recognized vegetal communities did not show evidences of human effects (v.g. maize pollen grains).