Phylogenomic approaches have recently helped elucidate various insect relationships, but large-scale comprehensiveanalyses on relationships within sawflies and woodwasps are still lacking. Here, we infer the relationshipsand long-term biogeographic history of these hymenopteran groups using a large dataset of 354 UCE locicollected from 385 species that represent all major lineages. Early Hymenoptera started diversifying during theEarly Triassic ~249 Ma and spread all over the ancient supercontinent Pangaea. We recovered Xyeloidea as amonophyletic sister group to other Hymenoptera and Pamphilioidea as sister to Unicalcarida. Within the diversefamily Tenthredinidae, our taxonomically and geographically expanded taxon sampling highlights the nonmonophylyof several traditionally defined subfamilies. In addition, the recent removal of Athalia and relatedgenera from the Tenthredinidae into the separate family Athaliidae is supported. The deep historical biogeographyof the group is characterised by independent dispersals and re-colonisations between the northern(Laurasia) and southern (Gondwana) palaeocontinents. The breakup of these landmasses led to ancient vicariancein several Gondwanan lineages, while interchange across the Northern Hemisphere has continued until theRecent. The little-studied African sawfly fauna is likewise a diverse mixture of groups with varying routes ofcolonization. Our results reveal interesting parallels in the evolution and biogeography of early hymenopteransand other ancient insect groups.