Turkey harbors a high diversity of viperid snakes, many with a high threat level on the International Union for Conservation of Nature (IUCN) Red List, yet perception about even basic topics, such as distributions and conservation statuses, remain poor. We initiated a multi-year project 7 y ago to compensate these shortcomings and present herein dramatically improved information on the status of mountain vipers of central-eastern Anatolia (Asian Turkey): Bolkar Viper (Montivipera b. bulgardaghica), Albizona Viper (M. b. albizona), Wagner's Viper (M. leagued), and partly Ottoman Viper (M. xanthina). The data originate from our fieldwork and a comprehensive search of all records available, including information from literature, online resources, locals, and herpetological experts. This resulted in 51 new localities, complemented by 36 published records, which were refined with new information, including four corrected/removed records and two records that were combined with new records due to their proximity. We summarized all records with precise information in a supplemented list of 85 localities, which is compared to current literature and the range maps available on the IUCN Red List of Threatened Species, the global standard reference for consultation on range maps and conservation status of species. Consequently, we report on large range extension of > 100 km in all four mountain viper taxa, increase the extent of occurrence for each viper taxon 4-8 times, reduce the distribution gaps between all pairs of parapatric, related, and ecologically similar mountain vipers, and discuss taxa delimitation, putative contact zones and conservation aspects.