There are 49 Marutas in number.
One evening, Diti, the mother of the Daityas was absorbed in thought. She was thinking about the many times her sons had been slaughtered by Indra and the devas. This made her really angry.
When her husband, Kashyapa, returned from his daily rituals, she asked him, “How come Indra and the devas always emerge victorious against my sons. How come, despite having brave sons who do a lot of penance, the devas always defeat them. Why?”
“It is because Lord Vishnu is on the side of the devas, Diti. You can’t do anything. Lord Vishnu will keep saving the devas,” Kashyapa said calmly.
“The power of penance is really strong. It can defeat anyone, even Vishnu. Grant me a son that shall kill that Indra. I will remain angry till Indra dies!” Diti yelled.
Kashyapa didn’t like Indra. He knew Indra was not an amazing king. But he disliked the Daityas even more. The order of the universe would only remain balanced if Indra remained king of the devas.
“You shall have the boon you wish for. But, you must observe a ritual while bearing a child. If you fulfill the ritual successfully, you child will destroy Indra,” Kashyapa said.
“You must perform this ritual for a whole year. During this time, you must not harm any creature. You can’t curse anyone, or tell a lie. You must not trim either your nails or hair. You must not touch anything that is unclean. You must not bathe by immersing yourself in water. Anger should also be under complete control. You must not speak to unworthy persons. You must always wear clean clothes, and you should eat anything that has previously been eaten by someone else. Eating meat is entirely forbidden. You must not drink water by taking it up in your hand. You must not go out at dawn or dusk, or without your hair being dressed properly. You must not sleep with your head to either north or west. You may not sleep without washing your legs, nor are you allowed to sleep with wet legs. You must always sleep alone, and must not sleep at either dawn or dusk. You must worship the household cow, Brahmins, and Laxmi before you eat in the morning. You must also worship those women whose husbands are still alive. You must also worship me, your husband,” Kashyapa explained.
“If you observe this Vrata (ritual/fast/penance), known as Pumsvana for a whole year, the son born then shall be the slayer of Indra and lead his brothers to victory,” he continued.
Diti soon became pregnant with the son she wanted. Aditi, the mother of many of the devas and Kashyapa’s other wife, learned about this and she went to Indra.
“Indra, Diti is having a really powerful son that is going to kill you, and you are just relaxing. If that child is born, you and all the other devas will be doomed,” Aditi said.
“I didn’t know about this, Mother. What do we do now?” Indra asked, alarmed.
“Diti is right now living alone. She is observing this ritual. If she breaks a condition of the ritual even once, she won’t have a child that kills you. You can go to her disguised as a servant. Then, once she breaks a rule of her ritual, you can kill the baby inside the womb,” Aditi said.
Indra listened to is mother’s plan and disguised himself as a servant. Diti accepted him as her servant. She thought he was a very devoted servant. One day, Diti was really tired and went to sleep without her washing her feet. This was violating the ritual. Indra took this chance and turned really tiny. He entered the womb and began slicing the embryo. He sliced into seven pieces. The baby suddenly started crying. Indra tried to silence the baby by saying ‘Ma Ruda’, which means don’t cry. But the baby kept crying. Indra got really frustrated turned the seven pieces into forty-nine pieces.
So, Diti gave birth to 49 sons, instead of one. They were called the Maruts because of what Indra had said in the womb: ‘Ma Ruda’. Since Diti had failed to fulfill the ritual, the Marutas became the companions and attendants of Indra, rather than his enemies.