MOVING AWAY

A civilization flourishes and suddenly it becomes uninhabited. Why does this happen and who causes it?

While Sri Rama and Laxmana were accompanying the great sage Vishwamitra muni to chastise the intruding  demons in the Yagna of the sages they crossed many places.  Vishwamitra muni told them about the history of the places that they crossed .He talked of Angamalaja a place where  Indra was purified by  the devatas and where Tataka was living. Such a famous place had now become uninhabited. 
The flourishing city of Mathura after Jarasandh's attack was deserted by the Yadavas.
Ayodhya was given up by Lava and Kusha and Kushasthali was made into a flourishing metropolis.
In due course Kushasthali was forgotten until Sri Krishna refurbished the city and named it Dwaraka. As time passed Dwaraka was inundated to the extent that people question it's existence today.
Even in medival history we hear about the great town of Hampi the capital of Vijayanagar which today has become a  historic place of ruins.
Shivaji's Raigad is reduced to a tourist spot.
Britain, who conquered almost the entire world has shrinking number of original Brits staying in London what an irony? 

This is a pattern of life creating something substantial so that eventually it remains in some obscure pages of history. The beauty and reality is that for the legacy to continue one has to keep doing what our ancestors have done knowing well enough that all creation has a limited life span but has a continuum of legacy. So the great Dharmik people create in a way as if what they create is going to exist eternally and simultaneously have the mental detachment after creation.
In living and leaving is an amazing harmony of life.
One gives meaning and the other gives feeling of non attachment.  Living gives legacy and leaving gives non attachment.