Why was the time difficult to determine in the Middle Ages?

In the Middle Ages, watches were already, but not very reliable. And it was possible to find out the time by the sundial only on a clear day.

Interesting fact: The first mechanical watch was a system of gears and hanging weights.

Wheel spinning wheels “came” to Europe from China and India in the 13th century. Like all useful inventions, they made life much easier for people - it was much easier to turn a wheel than a spindle. The first windmills were built in Europe in the 12th century. And in Persia, they appeared hundreds of years earlier.

Why did the Incas knit knots?

The Incas did not have a written language. For various “notes” and accounts, they used long multi-colored ropes. They tied knots on them, and all this was called a pile, or "nodal writing."

Not all Incas owned a “nodal letter”. Only children from the most distinguished families were taught him. Specialists still cannot decipher this secret language.