Complex sentence: Under New Forest regulations, mares and geldings may be of any breed; although the ponies are predominately New Foresters, other breeds such as Shetlands and their cross-bred descendants are also found in some areas.
Split into simpler sentences: Under New Forest regulations, mares and geldings may be of any breed. Athough the ponies are predominately New Foresters, other breeds such as Shetlands and their crossbred descendants can be found in some areas.