Why are women on periods not allowed inside temple

In Jainism, temple worship involves rituals that demand a high level of physical and mental purity from the worshiper, including direct contact with the sacred images. Menstruation is viewed as a state of impurity, and therefore women during their periods are restricted from entering the main temple or the cella where the images are kept. This practice is rooted in the belief that the sanctity of the temple and the ritual purity of the images must be preserved.