Ernst Prossy developed the class 629 for the Südbahn based on the class 229 2-6-2T tank locomotive of the Südbahn and kkStB. It had a leading bogie in order to be able to increase power while maintaining the axle and meter loads. With an unchanged driving wheel diameter of 1,614 mm (63.5 inches), they were suitable for passenger and light express trains. Approval was initially granted for 85 km/h and later increased to 90 km/h, and even 110 km/h was attained on test runs.

After the Südbahn had received 15, Gölsdorf also adopted the design with small changes for the kkStB and had 25 more built. Larger numbers were only created after the First World War, when the BBÖ, the ČSD and the PKP ordered greater numbers. The ČSD in particular ultimately made it to a total of 234 with its class 354.1 locomotives built by Škoda. These were characterized by two steam domes with a connecting pipe.