Sentence:  Natives voluntarily coming forward and entering in <WSD>encomienda</WSD> were excused from paying tribute for ten years; and, in any event, for the first two years after congregating in pueblos but one half the usual tribute could be legally exacted. 
Meaning of the word marked with <WSD> tags:  A system in Spain and, later and more extensively, in Spanish colonies, in which the right to exploit the labour of certain groups of subject people (initially, Muslims, during the Reconquista) was granted to conquerors; servitude within this system.