The immediate task of the occupiers was to gather the Jews together - to "concentrate" them. They were brought in from the countryside and concentrated in ghettos, which, by November 1940, were sealed.
In the summer of 1943, in the Maidanek concentration camp Isaac Schiper told a fellow inmate that
Everything depends on who transmits our testament to future generations, on who writes the history of this period.
Much of their work was lost. But much of it was also dug up years later - some was able to be preserved and is held as the Warsaw Ghetto Ringelblum Archives. From this has emerged "Poetry in Hell" - work that was sealed in milk cans and withstood being buried, lost and found many years later. At least one can is still missing, probably now under the Chinese Embassy in Warsaw.
This is an awesome testament to the human spirit, a testament to a people who saw plainly that the occupying nation intended to wipe them out, and who no doubt kept their hearts alight with the task of writing and saving their lore. More than 25,000 documents were found, probably at least as many more were hidden but lost.
Check out this site, and pay tribute for a moment to a people who were nearly annihilated but did everything in their power to save their culture.