They did nothing before 10,000 years ago, hunting and eating similar to any other animal on this earth.
Homo sapiens existed 200,000 ago, they spent 195,000 years just for hunting and eating
Some places continued to hunt and gather, well into the Iron Age, FearGod. It depends not only on tools used, but where they lived, geologically.
You do realise that not every places were suitable for agriculture, don't you?
The Arctic regions, the deserts, the Steppe are often regions that don't rely on agricultural farming. In the Arctic and Steppe, you don't find many permanent settlements like towns and cities.
To give you an example of the Iron Age nomads, for instance, the Scythians that occupied much of Eurasian Steppe.
The Scythians were nomadic people, from the 9th century BCE to 3rd century BCE, who following their grazing animals, horses, cattle and herds, stopping to allow them to graze, before moving on. And what they don't kill and eat what they owned, they would do hunting and gathering. They were the best hunters in the world, at that time.
You may think that this is poor way to live, but the Eurasian Steppe extend from China to what is now, Hungary, and the Scythians have actually prospered by controlling the Silk Road, for much of 1st millennium BCE.
The Scythians were known for their skills in metalwork. And in wars, they were renown for their ferocity, their marksmanship with the bow and their superior horsemanship.
Their empire outlasted their 1st millennium BCE, contemporaries, such as the Neo-Assyrian Empire, Neo-Babylonian Empire, the Persian Empire, and they were still formidable in the time of Alexander the Great.
The Scythians were hunters and gatherers as well as pastoral nomads. They were traders and warriors.
After Alexander, a new pastoral nomads, the Samaritans, forced them to eventual oblivion.
In the medieval period, when they reached Europe, the Mongols lived a similar lifestyle as that of the Scythians over 1000 years earlier. They hunt, they gather and they raised livestock just as Scythians did.