In the aftermath of the Japanese surrender and proclamation of Indonesian independence by Sukarno and Mohammad Hatta in August, 1945, the newly established Republic of Indonesia began to set up offices in East Sumatra.

Frustrated with the moderation of Republican politicians, the pemuda initiated a "social revolution" in March, 1946, killing much of the Malay and Simalungun aristocracy, sweeping away the former sultanate governments, and raiding the shops and warehouses of wealthy (often Chinese) businessmen.

A year later the invading Dutch felt that they could rely on the support of these groups in setting up a new government in East Sumatra that could compete for legitimacy with the Republic.

Twelve of the original thirteen members of the committee that formed to demand autonomy for East Sumatra following the Dutch invasion were Malays or Simalunguns.

[3] Following the Dutch-Indonesian Round Table Conference in late 1949, the Dutch withdrew military support from the State of East Sumatra and its local authority began to collapse.