Old English had a tendency to palatalize 'g' and 'h' -- especially in the middle of words -- to form growly sounds. 'G' could be sounded as a gutteral 'y'. In Middle English, when our spelling became mostly fixed, it was frequently written as 'gh', but that didn't stop the pronunciation from changing. By Early Modern English, 'gh' was pronounced (or not pronounced) in all kinds of ways, which is the reason we find funny Dr. Seuss's book title, The Tough Coughs As He Ploughs The Dough. At the same time, initial 'g' was often palatalized and tended to sound like 'y'.
This means we still have Modern English words based on duguth and geoguth, though you might not recognize them at first. Duguth survives in the related adjective "doughty," which describes a mature warrior's character: brave and hardy. Meanwhile, geoguth is the source of our English word "youth."