On 9 May 1940, the invasion of Belgium during World War II brutally interrupted the publication of Land of Black Gold. Tintin's universe was still young: Captain Haddock, Professor Calculus and Marlinspike Hall did not yet exist. Eight years later the adventure was re-started in Tintin magazine; with a couple of nifty tweaks, Hergé integrated into the story the new characters who had come along in the meantime. In 1950 the adventure was published as a book, and as the years went by and the world changed, a slightly updated version was released in 1971.