I dont see diference from older version of Indochina, but maybe you can create map of Mainland Southeast Asia, these its better then Indochina, becouse have more terittory, And including these country:
Cambodia
Laos
Vietnam
Peninsular Malaysia (comprising the southern end of the Malay peninsula but none of the Malay islands)
Myanmar (formerly Burma and part of British India until 1947)
Thailand (formerly Siam)
These will be new and very diferent map then Indochina,