European "Christendom" saw a high level of persecution of witches -- those supposedly practicing maleficarum or harmful magic -- which peaked especially from the mid 15th century (1400s) to the mid 18th century (1700s).
The number executed on charges of witchcraft is not certain and subject to considerable controversy. Estimates have ranged from about 10,000 to nine million. Most historians accept a figure in the range from 40,000 to 100,000 based on public records; there were perhaps two to three times that many individuals accused formally of or tried for witchcraft. About 12,000 executions have been identified in existing records.
About three fourths of the executions based on witchcraft accusations were in the Holy Roman Empire, including parts of what are today Germany, France, the Netherlands and Switzerland. The peaks of accusations and executions came at somewhat different times in different regions. The most executions in Europer, by number, for witchcraft were in the period from 1580 to 1650.
Why Mostly Women?
About 75% to 80% of those executed were women. In some areas and times, mostly men were accused; in other times and places, most of the men who were accused or executed were connected with women who were accused. Why were most of those accused women?
The church itself saw witchcraft alternately as superstition that undermined church teachings and thus the church, and as real agreements with the Devil that also undermined the church. Cultural assumptions were that women were inherently weaker, and thus more susceptible to either superstition or to the Devil's approach. In Europe, this idea of women's weakness was tied to the story of Eve's temptation by the Devil, although the story itself cannot be blamed for the proportion of women accused, because even in other cultures, witchcraft accusations have been more likely to be directed at women.
Some writers have also argued, with significant evidence, that many of those accused were single women or widows whose very existence delayed the full inheritance of property by male heirs. Dower rights, intended to protect widows, also meant that women at a vulnerable time of life had some power over property that women usually could not exercise. Witchcraft accusations were easy ways to remove the obstacle.
It was also true that most of those accused and executed were among the poorest, most marginal in society. Women's marginality compared to men added to their susceptibility to accusations.
To learn more about the witch hunts of European culture, follow the progression of events in the Timeline of European Witch Hunts, check out the history of the Malleus Maleficarum, and also check out the events in the English colony of Massachusetts in the Salem witch trials of 1692.
For more depth, you'll want to look at the detailed studies of this episode in history: see the Bibliography on European Witchcraft Persecutions includes many of the major historical studies.