Beeball

Beeball is the earliest and simplest variant of baseball offered by theRoyal Netherlands Baseball and Softball Federation. Even though the KNBSB suggests children can start playing Beeball at five, as opposed to at six for peanutball, the true advantage of beeball over peanutball is the smaller required minimum team size (five), enabling those clubs with too few very youthful members to field a peanutball team to field a beeball team.

source: http://www.knbsb.nl/index.php?option=com_content&task=view&id=1402&Itemid=414