While some times, archaeologists can speak with confidence about cultures and dates, more often, the development of chronologies for the cultures of the region is comparable to assembling three-dimensional jig saw puzzles from pieces which often mixed, jumbled, broken and missing. Widespread cultures evolved in different directions at different rates. External cultural influences had different degrees of impact on different cultures over time. Definitions of different cultures mean different things to different archaeologists. Cultural boundaries are elusive.
Cultural chronology is a moving target.