I highlight two squamate lineages endemic to Southeast Asia, the Asian water monitors (Varanus salvator Complex) and the Angle-headed lizards (Agamidae: Gonocephalus), and elucidate their systematic affinities and historical biogeography. My results represent novel phylogenetic inferences, with biogeographic histories and diversification events corresponding to major climatic fluctuations over the past 30 million years. Additionally, I solidify the taxonomy and systematics of the Varanus salvator Complex, and enumerate more than a dozen Gonocephalus lineages as candidate species in need of taxonomic scrutiny. Lastly, I investigate contemporary and historical patterns of dispersal throughout Sundaland, and between Sundaland and the Philippines.