The Pandavas are already there in five places.. named Thrichittattu (Yudhishtira) Thrippuliyur (Bhima) , Thiruvaranmula (Arjuna)Thiruvanmundur (Nakula), Thrikkodithanam(Sahadeva), and when lord came.. all of them got up and given their place to lord is what people believe..
The day Lord Krishna reached Aranmula is 4th day of Thiruvonam.. All village came out to receive Krishna to their place.. They came in Snake boats.. Thus begin the Ulsavam of Uthrattathi Vallom kali…
Even now people celebrate irrespective of their religion.. Every one on their own Snake boat comes to Aranmula and do take part in the Jalolsavaghoshayathra.. and then return… to their respective places..