- Mangala sutram literally means "an auspicious thread" which is knotted around the bride's neck. It is usually a necklace with black beads strung from a black or yellow thread prepared with turmeric. Sometimes gold, white or red beads are also added to the mangala sutram, depending on regional variation. It is a symbol of marriage worn by women.
Mangala sutra's origin dates back to the 6th Century AD as a single yellow thread was tied around the bride for protection from other men and evil spirits. Mangala sutra is a social practice widespread in India, Sri Lanka, and Nepal.
Ref - https://yehaindia.com/indian-traditional-jewellery-from-head-to-toe/