Short answer: Jainism does not teach that women are inherently impure because of menstruation. The idea of ritual impurity tied to periods is not a core Jain doctrine. However, practices about entering derasar/temple during menstruation vary by tradition and local custom.

• Digambaras: Some historical and regional practices have restricted menstruating women from certain temple rites or from entering the main sanctuary in some communities. This is a cultural/custom practice in some places, not a universal scriptural rule. The Shwetambar tradition generally allows menstruating women to participate in temple activities, though local norms may differ.
• Shwetambaras: In most communities, menstruating women are not barred from entering the temple or from participating in temple worship, though individuals may choose to observe personal or family practices during their period.

Key point to keep in mind:

• The core Jain emphasis is on ahimsa (non-violence), tapas (austerity), and purushartha (spiritual effort). Periods are a natural biological phase and are not considered a sin.
• Concrete rules about temple access are not fixed in Jain scriptures; they arise from community customs, which can differ by region, caste, and Jain school.

If you’d like, I can check for specific texts or passages from Digambara and Shwetambara sources to show how they describe purity, and I can point you to authentic JainKnowledge resources that discuss temple practices and menstruation.