She married first Siegfried I of Weimar-Orlamünde and then Otto I, Count of Salm.
She was regent of the County of Weimar-Orlamünde during the minority of her son Siegfried II of Weimar-Orlamünde in 1113-1115, and regent of the County of Bentheim on behalf of her daughter Sophia in 1150.
She was the daughter of Henry, Margrave of Frisia and Gertrude of Brunswick.
[1] Gertrude had two full siblings: Otto III of Northeim, who succeeded her father, and Richenza, who married the future Emperor Lothair II.
[4] Part of the reason Gertrude married Otto was to secure a male protector for her underage sons, Siegfried II and William.