The Alt-Oldenburger and Ostfriesen are representatives of a group of horse breeds primarily from continental Europe called heavy warmbloods. The breed has two names because the same horse was bred in two regions in the most north-western part of Germany: East Frisia and the former grand duchy of Oldenburg. The name "Alt-Oldenburger" - alt meaning "old" - simply distinguishes this horse from its descendant, the modern Oldenburg, which is bred for sport.

The heavy warmbloods are a group of horse breeds primarily from continental Europe. The title includes the Ostfriesen and Alt-Oldenburger ("Old-Oldenburger"), Groningen, and similar horses from Silesia, Saxony-Thuringia, and Bavaria. Breeds like the Hungarian Nonius, Kladruber, and Cleveland Bay are also often classed as "heavy warmbloods." They are the ancestors of the modern warmbloods, and are typically bred by preservation groups to fit the pre-World War I model of the all-purpose utility horse. Unlike the registries of the sport horses that followed them, many heavy warmblood registries maintain closed or partly closed studbooks. However, external evaluation and performance testing of the breeding stock is still a key element in these registries. Many of the heavy warmbloods are selected primarily for family-friendly temperaments.