Much more is now known about early Cuban jazz bands, though a full assessment is plagued by the lack of recordings. Migrations and visits to and from the USA and the mutual exchange of recordings and sheet music kept musicians in the two countries in touch. In the first part of the 20th century there were close relations between musicians in Cuba and those in New Orleans. The orchestra leader in the famous Tropicana Club, Armando Romeu Jr, was a leading figure in the post-WWII development of Cuban jazz. The phenomenon of cubop, and jam sessions in Havana and New York, created genuine fusions which still influence musicians today.