Civilizations rise and fall and this is an unusual and in fact a natural phenomenon. But life goes on forever. Many of the ancient civilizations have not continued and died out but some aspects them still live on to date. And some civilizations lose a lot and new cultures, religions, beliefs or technologies of newer civilizations affect them a great deal.
In Nepal also we had some cultures wherein ancient beliefs, farming mechanisms still survive. We have a tribal community called Route and unfortunately, they are not only losing their ancient systems, beliefs, and cultures to the mainstream civilization but also they are losing their demographic size gradually.
Yes, there are still some cultures totally different from mainstream Nepali culture they are also gradually losing their ancient beliefs, customs, and cultures. The world is in constant flux. And everything in their transition and evolution and or else humans cannot survive if they cannot adapt to a changing environment or cultural or global demand.
It is interesting to know something about an ancient civilization which is almost extinct and yes a few ruins or remains are seen in America. They have lost lots of their ancient systems and cultures to Roman Catholics.
They are a native people of Mexico and Central America. The Maya have populated the lands. And while the Maya are losing gradually everything they had called their customs, but a little still remains with some people living there but it has assimilated most of what we call Christian civilization.
They had a very ancient culture and of course. Like other religions, they had a belief in heaven and they have the nine levels of the underworld and the thirteen levels of the higher world which is paradise.
They have many pyramids and they believe in the cyclical nature of human existence and birth and death are understood in that light. Most of their ancient texts have been burned and only a few remain to date. Today, of course, something of this ancient civilization remains and yet there is a mingling of Christianity in their culture and yet some aspects of the Maya and their beliefs and cultures in some parts still continue.