Monday answer
It may come as a surprise to you, as it did me, but the country is old RUSSIA and the black flag (and torches) was a FIRE signal. (The signal may have originated from the Mongols who used black and white flags as a cavalry semaphore system.) The system was a series of tall wood towers located around most (if not all) of the major cities like Kiev, Moscow, Novgorod.
Russia had little in the way of technology and most of the population had zero access to specialized tools, but they had millions of acres (or whatever they called them then) of timber. As such, peasants were taught to use an ax and chisel from a very early age. They barely used nails or other fasteners, but relied on timber framing to build. They were very good at it. It is said that the structures were so good and the workers so accomplished that they regularly took out doors and walls in small structures for celebrations of all types -- then put it all back after it was over. It was not unusual for even eating utensils to be made very quickly by ax alone. Unfortunately fire was a problem with thousands of wood structures that often, owing to the long winters, were linked together by doors, hallways, covered passages and linked plank floors. With hundreds of open mud ovens in hundreds of homes, fire happened so often that precut to size logs were stored at the ends of �city� streets so that whole rooms, even a whole �izba� (house) could be built very quickly from the city stockpiles by simply dragging the sized logs from the storage depots to the new location.
For that time, the Russians, by numbers, were some of the best woodworkers around, in spite of the absence of more sophisticated tools. They still maintain that reputation in the rural areas today where life is centered at some sort of farm. Also, still existing the Russian wooden churches remain famous for their fine construction. It wasn�t until 1725 in the new capital St. Petersburg that stone buildings supplanted wooden structures.