A furlong is 220 yards. That is closer to 200 metres. One hectometre is 100 metres. So, think of a furlong as two hectometres. A rood (or rod), a pole, and a perch are local measures. They vary from six to eight yards.
The French invented the metre because their measures varied. The league in Paris was not the same length as the league they used down South. I lived in Enfield for many years. There was an Enfield inch because we had an arms factory and when you make firearms, you want to make them accurately. However, other people in Enfield used an inch that was longer or shorter than the one used at the Royal Small Arms Factory.