[15][16][17][18] Contrary to several historians of the late 20th century, Heather contends that it was the movements of "barbarians" in the Migration Period which led to the collapse of the Western Roman Empire.
Heather's approach differs from many of his predecessors in the late 20th century, who have tended to downplay the importance migration played in the fall of the Western Roman Empire.
[12] Guy Halsall groups Heather together with Neil Christie and E. A. Thompson as being among the so-called Movers, who trace the collapse of the Western Roman Empire to external migration.
[20] Along with Bryan Ward-Perkins and other scholars affiliated with the University of Oxford, Heather belongs to a new generation of historians who beginning in the early 2000s started to challenge theories on Late Antiquity that had been prevalent since the 1970s.
Michael Kulikowski, who is sometimes associated with this group, has said Heather promotes a "neo-Romantic vision of mass migrations of free Germanic peoples" and wishes "to revive a biological approach to ethnicity".
"[25] Guy Halsall has identified Peter Heather as the leader of a "counter-revisionist offensive against more subtle ways of thinking" about the Migration Period.
[26] Halsall writes that Heather and the Oxford historians have been responsible for "an academic counter-revolution" of wide importance, and that they deliberately provide "succour" to far-right extremists such as Anders Behring Breivik.