The claim to land ownership was central to the cultural groups that came to our island. The earliest to arrive of course had "first dibs", when they settled and occupied the land. The "open spaces" thus became distinguishable by boundaries, based upon these claims to ownership.
Land ownership initially centered around the family units that occupied, farmed, had their young, grazed their animals upon, and buried their dead within [or upon] the land. Generations evolved that came to expect this land would be passed down to the next generation. Conflicts frequently arose when one member of the family thought they owned, or deserved, a sections of land that another family member claimed. Family feuds would arise creating all sorts of dilemmas for the greater good. Keeping everyone happy was a real challenge. Where are these boundaries anyway? Who is going to make me stay on my side of fence? Who's in charge here? I'll just take it! No one can take it form me! My might makes right!
The family groups that got along together would seem to have a better chance of survival. Frequently, one family member [or several] became the head and judge of these land disputes. [Or other family disputes as well.] His, or their, decision(s) would become the common practice of the family group, thus establishing some sort of order and authority among those living upon the land. If these decisions worked well, they might be adopted by other family groups or passed down to the next generations. Ultimately, a land holding system would be in place allowing for a more stable environment. These decisions, and others, became the common practice of the tribe...the beginnings of "common law".
Now it became evident very early, that one would soon have to figure out a way to measure this land and its boundaries. The farmers seem to have started things off, by using the corn plant that all would have grown and eaten. A kernel of corn held in the hand could be see by all and understood. [Grains of barleycorn were uniformly equal in size!] Three lengths of barleycorn was to equal one inch! Nine barley corn lined up in the palm of the hand was called a "palmbreath", and three "palmbreaths" would equal a foot. There were to be three feet in the step, and three steps in the leap. Three leaps would be called the land. [used as a measurement] A thousand lands in the mile. So 3000 leaps would be a mile! Gee, leaps and bounds! More to come.
These measurements are taken from "Hywel Dda The Law" translated by Dafydd Jenkins, Gomer Press, 1990. pp. 120-122.