Family camps sprang up in eastern Poland, west Byelorussia, and the western Ukraine: all areas with dense natural forests. The camps existed to resuce European Jews, in contrast with the partisan units, whose aim was to fight the Germans from the rear. The family encampments relied on the fighting force of the partisans for defense. The camps suffered from the hostility of the surrounding peasant population and their number remained small. Although we can only confirm the existance of a small number of small camps and a few larger ones, there were likely others, but not evidence to prove their existence.
The family camp run by Tuvia Bielski was the largest, with 1231 inhabitants. As a boy, Tuvia joined the pioneering youth movement and enlisted in the Polish army in 1928. After his parents were killed in the Novogrudok ghetto at the start of the war, he took to the forests with his brothers Zusia, Asahel and Aaron, where they formed one of the first partisan units. He sent messengers to the ghettos in that area, warning of the imminent murder of the Jews, and calling on people to join his group.
Sources: Ghetto Fighters House