nineteen hundred sixteen hundred But!: two thouand

1900 could be pronounced as "nineteen hundred". "nineteen thousand" would be 19,000. As for the correct way it varies based on the context. I suppose officially 1900 would be "one thousand nine hundred" but most people would just say "nineteen hundred".

The correct way is: Nineteen hundred and no you should not say nineteen thousand, as people will not understand you. 1600 = sixteen hundred. In a sentence: "In the year 1900, the world was introduced to the world's first underground train system"

Nineteen hundred, the correct one I think..