Polygamy has most likely existed from the beginning of Hindu culture, given its primarily patriarchal nature.
Both the major epics, the Ramayana and the Mahabharata, as
well as the historical record, testify to the practice.
The dharma literature allows men to marry women of lesser
social level if their previous wife was of equal social standing.
Despite the fact that polygamy existed, it was most likely
uncommon and limited to men of great position and financial means who could
sustain many families.
When the first wife was unable to have children, one of the
few reasons for choosing a second wife was to try to father the boys required
to perpetuate the lineage and assure performance of the ancestral ceremonies.
