The Tripartite Wizarding Commonwealth of England, Scotland and Ireland, at the time referred to as simply the Commonwealth and now known as the Old Commonwealth, was the official name of the wizarding government of Great Britain and Ireland from 1649 to 1660; the first structured government body in Britain, and the true precursor to the modern Ministry of Magic. It rose from the English Wizarding Revolution, where a conglomerate of powerful wizarding families, led by Salomon Lestrange, took control of the Wizards' Council and created a unified, structured government in place of the old, ineffective council.

The Commonwealth idea proved to be quite revolutionary by tearing down the English oligarchy over the Isles; allowing Scottish and Irish wizarding families to take part in the government, rooting out corruption that flourished during the Council era and streamlining government process to make for easy insertion of new laws and actions. Although initially popular and effective, the young Commonwealth was soon transformed into a brutal dictatorship after founder Salomon Lestrange; gradually descending in the realm of Dark Magic, proclaimed himself as Lord Malastaire and purged the government of those he deemed to be his enemies. With aid from the Malastaire Minutemen; a government paramilitary organization under direct command of the Dark Lord, he instituted a reign of terror that lasted over half a decade, murdering any who opposed him without hesitation.

Malastaire's reign of terror came to an end in 1659, when double-agent Julius Prince; then Headmaster of Hogwarts, and a small army of rebels stormed his castle and engaged him in a duel to the death. Prince was successful, and he was named Interim Plenipotentiary of the Commonwealth. Although Prince tried to save the Commonwealth, the fear bred from Malastaire's reign of terror made people too afraid of such power in the hands of so few people, and it was decided by general vote (which is, as of 2017, unanimously regarded as fraudulent) to dissolve the Commonwealth in favour of the reestablishment of the Wizards' Council.