four thousand years (see Molina); literally, ten times 400 years (SW)
Orthographic Variants:
matlactzonxiuitl
Alonso de Molina:
matlactzonxiuitl. quatro milaños. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 53r. col. 2. Thanks to Joe Campbell for providing the transcription.