This is an impression from Dwapara Yuga where in Shri Krishna, Lord Narayana himself, killed the demon Kamsa, his maternal uncle and made Ugrasena, his maternal grandfather, the king of Mathura. Enraged by this, Kamsa's father-in law, Jarasandha (the king of Magadha) together with his friend Kalayavana attacked Mathura 17 times. For the safety of the people, Krishna along with the Yadavas decided to move the capital from Mathura to Dwaraka. Just that Krishna had shifted from Mathura do not assume that Krishna was inefficient to protect his own men; it was his benevolence to give his people a better place and a well-planned city with utmost facilities which they had never enjoyed. Shri Krishna and the Yadavas left Mathura and arrived at the coast of Saurashtra.
They decided to build their capital in the coastal region and invoked Visvakarma, the deity of construction. However, Visvakarma said that the task could be completed only if Samudradeva, the lord of the sea, provided some land. Shri Krishna worshipped Samudradeva, who was pleased and gave them land measuring 12 yojanas (1 yojana=8 miles) and henceforth, Visvakarma built Dwaraka, a city in gold. Kushasthali puri was situated on the western coast where river Gomati met the ocean. Dwaraka was located exactly at this estuary. It was galvanised by the majestic presence of Lord Krishna. Dwaraka was a graceful place to live in with beautiful gardens, well organised roads, highly furnished walls and magnificently built up structures which portrayed the elegancy of the then engineering techniques.
The citizens even had an identity card with three lion heads engraved on it. In a nut shell, it was a place where everything from bread to bed was extravagant and lavish. Everything was going till then. Yadavas could not realize that their fate would be sealed over. Their chapter was getting to be closed. For this being executed promptly, Yadavas along with Balarama and Krishna moved to Prabhasa. They bathed there, indulged in a war which was sparked by Vaasudeva.