Where did the idea of "witchcraft" come from?

It couldn't really have came up from no-where..could it?

The Devil

in the middle age the people were stupid and believed in magical things

Cults in the past like the ancient times have practiced such things.

There are still some satanic and vicuna cults that do such things today but they are very small and just about of the claimed causes of it such as games and movies involving magic (Harry Potter & Magic the Gathering) or RPGs (Like D&D) have been pr oven to in fact lure people away from such things.

Witchcraft will always be around but it will over time be part of a smaller minority than it is already.

Witchcraft dates back as early as the ancient Celts, even in ancient Egyptian times and Druids, and was originally a nature based religion wherein people gave reverence to the elements for the animals and vegetables they ate. You can learn more about the history of witchcraft by reading the simple overview at http://ca.essortment.com/historyofmagi_rsav.htm today it is still basically the same, except for the Hollywood stuff that has given it a bad name, along with ignorant people who insist that it has to do with the devil. Real witches know that there is no such thing, negative energy is what you make of it.

The Goddess.?

Witches and Warlocks

I agree a little with Saya but witchcraft has also been found in ancient Babylon and other ancient civilizations it true age is lost in the passage of time it has been found in every corner of the world and is the oldest known religion it easily predates Christianity, Judaism, Hinduism and Buddhism.

it's many thousands of years old.

Older than Celts, or Egyptians.
A Warlock is a betrayer and oath breaker not the male version of Witch.
Witch means a man or woman.

its based on the power of nature and gives of the other world have a look at WNW.dragonsbreathblessings.com

It all started with ancient pagan practices..