Tribes had blacksmiths and thus weapons. I can understand how they forged them as it likely wouldn't have been that hard. But what I don't get is where they got their iron.
Did the tribes have mines? Did they trade for them? I honestly have no idea and the internet isn't helping me. For context, I'm referring to around the time of Genghis Khan but not the Mongols specifically.
Mining goes back a long way – there were tin mines in Cornwall before the time of Christ – but the major source of iron in the earliest periods was not mines, but bogs, where an ore known as "bog iron" could be readily harvested.
There is always more to be said, of course, but while you are waiting for fresh answers to your query you may like to review these earlier responses, which explain how the ancients sources their iron:
From where did the early Romans receive their Iron?
and How iron mining differed from bog iron harvesting?, all led by u/wotan_weevil