Limbu ni beauties.
Folks here's some significants about Kirat religions which has not been incorporated into Vedic Hinduism. While worshiping of nature(snakes, stones, etc has been seen as Kirat religion being incorporated into Vedic Hinduism) which relates to Sivaism, kul puja or pitra(ancestors worship) and udhauli puja( mother worship) has escape being incorporated into Veda somehow. Here's some answers collected from Kirati elders.

1. What is Kul puja?

Kul puja is the worshipping of one’s ancestors. While there are variations in kul devota worship, these activities have one thing in common. They are a means of ensuring prosperity, good fortune, and appeasing the gods and ancestral spirits. Given the importance of the rites for the well-being of the descent group, it was the social obligation of every household that possesses the necessary resources to hold kul devota worship, to sponsor the ritual activities

2. What is Udhauli puja?

Udhauli puja is the worshiping of mother goddess. Udhauli means going down. It is believed that from this day the winter season starts. So people, birds and animal migrate from cold regions to warmer regions. This kind of migration occurs twice in a year. The celebration of migrating downwards during this season is called “Udhauli" and the celebration of migrating upwards during the season of Baisakh (April or May) is called “Ubhauli". This has been going on since the dawn of the mankind which time is immemorial. Still today, animals and birds migrate depending on the season.

This event is also called “Bhumi Puja” (Worship of Land) where Kirat people worship mother nature asking for good cultivation of crops during the season of April( Ubhauli) when people starts to sow crops and thanking the god for giving good crops during harvesting before the cold seasons start to turn in (Udhauli). This event of Kirati people has also been stated in Mundhum (holy book of Kirati people).

3. Why do the Rais and Limbus bury their dead instead of cremating them in the ghats?

It is because it is the right thing to do. The Mundhum states that “God had made your body out of the earth and ashes and today your body is mixing with the earth again.”
When a male member of a family dies, his corpse should be washed and wrapped with a white shroud and put into a wooden coffin, “ Khong” and should be covered with, “Khuk” in such a way that the face of the corpse can be seen from outside. The head of the corpse should be exposed and be sheltered with a kind of cap or hat or umbrella, “Saklip”. The coffin should then be buried within a stone box under a four feet deep pit. All the mourning members who attend the burial ceremony should offer a last handful of earth to show their last respect to the dead person and the following should be chanted, “God had made your body out of the earth and ashes and today your body is mixing with the earth again.” After covering the pit with earth and stones, the grave should be piled up with four steps of stones for the man and three steps for the woman. A stone pillar should be erected in the middle of the grave. If the man is of high regard, his stone monument should be raised to eight or nine steps high in his honour. The death ritual of Kirat people is stated in Mundhum (holy book of Kirati people).

4. Why do the Rai and Limbu offer cooked meat to all at the last rites of the dead person?

The cooked meat is not for the people gathered for that ritual. It is offered to the departed soul. So is wine and all kinds of food items offered.

5. Why do the Kirat people instead of incense, dry Tetepati leaves are burnt?

The Tetepati leaves are from trees, and trees have been always been there since man was here on earth. That’s why Kirat are nature worshipers.

6. Why do Rais and Limbus used hot iron rod to rip the heart of pig and why do Kirat people eat pig and buffalo which are taboos to tagadharis group?

The hot iron rod is the quickest, least painful and cleanest way to kill one. In early ages, Kiratis were hunters and mountaineers. They hunted animals for food with arrow and spears. Wild pigs and buffaloes thrives in the forests and plains and Kirat people have always hunted these animals. Later the pigs and buffaloes were domesticated for easier source of food. Pork is used for auspicious such as wedding and holy occasions in Rai and Limbu culture.

7. How is the marriage ritual for Rai and Limbu or of Kirat culture like?

Love marriage with agreement between both partners is common. Whatever the type of marriage, however, those from the boy's side have to go with alcohol and gifts (sagun) to the girl's house and ask for their consent and offer apologies. The Rais do not marry their maternal uncle's and aunt's daughters, though there is a practice of marrying one's windowed elder sister-in-law. The main marriage ceremony takes place in the house of the groom among the Kirat's communitities which is distinctly different from the practices of the Tagadhari marriage which takes place in the bride's house.

8. I learned that some Kiratis will become ill if they happen to eat goat meat? Why is that so?

It again revolves around Kul Devota and Kirateswor which is all powerful and in existence. The Kirateswor and Kul Devota have to be appeased. The Kirat communities extensively use alcohol not only in social activities but also in religious activities.

9. Why do Rais and Limbus used wild bamboo containers to store wine and jaar(millet beer)?

There were no luxurious jar or glass containers to store wine and jaar(millet beer). Hence Kiratis made whatever nature gave them. Hence nature worshippers.

10. How come they don’t use all those religious offerings like other Hindus do?

Kiratis are nature worshipers and they practices are simple and not complex that those of Veda religion.