Because of poor economic conditions and a rapidly growing population in Isan, a large number of Lao migrated to Bangkok. It was not until the administration of Field Marshall Phibul Songkhram after World War II that mo lam performances were staged in Bangkok. In 1946 a mo lam performance took place at the Rajdamnoen Boxing Stadium which was first advertised by sound trucks. Migrant Lao, upon hearing their music, followed the trucks to the stadium where nearly three thousand people heard the performance.