For countries that have undergone partition, the PGE estimates for a given year include all of the origin country’s then-current territories. This means that for dates before partition, all of the once united territory is included: estimates for Sudan before 2011, for example, include present-day South Sudan.
Where survey data are available from before the breakup for the territory of successor states, these data have been used to generate PGE estimates like anything else in the source data (the DCPO routine does not make any effort to incorporate information from the origin state into estimates for the successor state). For example, the estimates for Russia for dates before the breakup of the Soviet Union are for the territories of the USSR that would become Russia after the breakup; there are similar pre-breakup data available for several FSU states, the Czech Republic and Slovakia, and a few successor states of the former Yugoslavia. The resulting estimates are available for use when appropriate, that is, to match the conventions of the other data one may be employing.