Sentence:  [...] <WSD>Archaic</WSD> Stage [...] the stage of migratory hunting and gathering cultures continuing into environmental conditions approximately those of the present. 
Meaning of the word marked with <WSD> tags:  A general term for the prehistoric period intermediate between the earliest period (‘[http://en.wikipedia.org/wiki/Paleo-Indian Paleo-Indian]', ‘Paleo-American', ‘American‐paleolithic', "&c".) of human presence in the Western Hemisphere, and the most recent prehistoric period (‘Woodland', etc.).