Final answer:
The Crusaders targeted Jewish communities in Europe before embarking on their expeditions to the Holy Land, these attacks were influenced by religious rhetoric that left Jewish populations exposed to violence and extortion.
Step-by-step explanation:
Before the Crusaders had even left Europe during the Crusading period, it was not the Muslim or Christian communities they attacked, nor the Zoroastrians who were by then largely absent from Europe. Instead, the initial violence targeted Jewish communities, particularly those in the Rhineland.
This brutal conduct was influenced by religious rhetoric and the wrongful association of Jews with non-Christians, making them vulnerable to attacks from those who sought to extort and plunder under the guise of religious warfare. Additionally, figures like Peter the Hermit compelled German Jewish populations to provide supplies to their crusading bands. Although the Church condemned such violence, these events marked the onset of an era filled with precarious times for Jewish communities in Christian Europe.