What is the feud between the families of Ulrich von Gladwitz and Georg Znaeym?

The families of Ulrich von Gladwitz and Georg Znaeym have been engaged in a bitter feud for generations. Their beef relates to an old land dispute whose precise details have been lost in the mists of time. But however it started, this epic conflict has raged down through the years, passed on from generation to generation, each one more determined than the last to uphold their families' honor.
Now you might think that such a serious dispute could only possibly arise over a substantial piece of land, a valuable plot with extensive game and fish, or even perhaps large mineral deposits. But no. The land in question is nothing more than a narrow strip of woodland. Yet this small plot of land is enough to form the basis for a seemingly never-ending conflict between two warring families. This piece of "precipitous woodland" has become a symbol of family pride. After several generations of feuding it's no longer the land itself that's important but the principle it represents.