Note: Do not rely on this information. It is very old.
Platt Deutsch
Platt-Deutsch, a term applied to the dialects of the North German and neighbouring lowlands, and formerly extending from Holland to Russian Poland, and touching the borders of Denmark upon the N. The Heliand (a production of the 9th century) marks its first period, while the immediately succeeding period is poor in literature. Reincke Fuchs and the Flemish Uilenspiegel may be classed as Platt-Deutsch. In the 16th century it was employed in history and theology. Klaus Groth and Fritz Reuter have given much impetus to the modern Low German.