Is it permissible to travel to another country to seek knowledge, leaving one's parents behind, in a situation where ignorance and Bid'ah (innovations in religion) are widespread in the country of residence?

Obedience to parents is obligatory, unless it conflicts with obedience to the Creator. If seeking knowledge is an individual obligation (fard ayn), then there is no obedience to them in refraining from traveling to seek it, unless the parents would be harmed by your absence. However, if seeking knowledge is a communal obligation (fard kifayah), then it is permissible to travel to seek it without their consent, though it is better to appease them and explain the reasons for your travel. If there is someone among your siblings who can care for them, then there is no impediment to your travel for seeking knowledge.