Why did the Shwetambar Jains forget Mandargiri?

While researching upon the forgotten “ Vihar Bhumi’s ” of Lord Mahavir (places where Lord Mahavir traveled during his lifetime), I came across a hill named “ Mandargiri ”. What fascinated me was the fact that this hill that was the actual place where the 12th Tirthankar, Shri Vasupujya Swami attained Nirvan / Moksh (salvation) . As I had always read that Champapuri tirth (situated in Champanagar village, Bihar) was the place where all the 5 Kalyanak’s of Vasupujya Swami took place, this bit of information was absolutely new for me. Therefore, I decided to pen this article in a Q & A format to uncover the facts properly. How old is the Champa city? What are the scriptural evidences that show that all the 5 Kalyanaks of Lord Vasupujya Swami took place here? It is believed that the first Tirthankar, Lord Adinath had divided the country into 52 Janapadas (kingdoms) and one such Janapada was known as Ang whose capital was Champa . This fact is also corroborated from Mahabhar