Pachacuti was a Sapa Inca (the leader of the Inca), who transformed the Kingdom of Cuzco into Inca Empire.
Ayllu is a traditional community in the Andes, as as a community of Quechuas or Aymaras.
Mita was a mandatory public service in the Inca Empire.
Quipu was the system of knots that the Inca used to count.