Gene sequencing wasn’t really a thing (at least an affordable thing) until the 2010s, but once it was widely available archaeologists started using it on pretty much anything they could extract a sample from. Suddenly it became possible to track the migrations of groups over time by tracing gene similarities, determine how much intermarrying there must have been within groups, etc. Even with individual sites it has been used to determine when leadership was hereditary vs not, or how wealth was distributed (by looking at residual food dna on teeth). It really has revolutionized the field and cast a lot of old-school theories (often taken for truth) into the dustbin.