hi! it would be helpful if you could identify the region & date range you're interested in, but meanwhile you can get some ideas from these sections of the FAQ
Communications - see under Carrier Pigeons
Generally, they communicated by couriers: sometimes men on foot (such as in the Battle of Marathon, hence the word marathon), and often men on horses.
There were sometimes wilder inventions put into practice, such as Napoleon's "Chappe Telegram," which were steel arms mounted on top of towers which communicated and spread messages by the position of the arms (see The Information: A Theory, A Fire, A Flood for an exceptional account of this technology). Additionally, messages could be spread by Drums (particularly in Africa, though occasionally used in other cultures) or by smoke signals.
But this is an incredibly broad topic, and to get the information you need you might have to focus your question.