The term 'extremist groups' can mean many things, even how extreme you mean. You also don't specify from what or where they might be banned, or even what country where laws can vary widely.
A general rule for basis to ban a group:
In most places, people (an extremist group being a group of people) have a right to their opinions, to speak them or to publish them. In many places, and in most cases, people have a right to demonstrate to deliver their message as long as they're complying with the laws of that place. Where their rights end is when they infringe on the rights of others or cause harm to others. Using these guidelines, you may be able to answer your own question.
The major goal of radical religious and cultural terrorist groups is the destruction of perceived enemies or opposition that stands in the way of their ideological beliefs. This can include individuals, institutions, governments, or societal norms that do not align with their extremist views. The ultimate aim is to create fear, chaos, and instability in society to further their agenda.
A violent subculture refers to a group within a society that promotes or glorifies violence as a way of life or as a means to achieve their goals. Members of this subculture often engage in activities that involve aggression, destruction, and law-breaking. Examples include gangs, extremist groups, and certain criminal organizations.
The reasons groups of people leave a particular place are called push factors. Push factors are usually due to a difficulty such as war, natural disasters, food shortages, or inability to find jobs.
People may commit acts of violence for a variety of complex reasons such as mental illness, a desire for retaliation, or as a result of being influenced by extremist ideologies. It is important to address underlying issues such as access to firearms, mental health support, and social inequalities to try and prevent such violence.
Some people might move because of the pull factors pulling them toward that place. They might also move because of the weather conditions where they live.
Extremist Groups was created in 2002.
extremist group
Issue-oriented groups
There are many reasons, here are just a few. They believe it is the only way they will be listened to. They want power and to impose their views on others. They believe they are being persecuted. They are insane. Because they can.
about peace they both are the same and also both have some extremist groups.
It led the United States to offer weapons to extremist leaders who fought against the Soviet occupation of Afghanistan
When someone is an extremist, it means that they go to extreme lengths to prove a belief that other groups of the population disagrees on. And by extreme lengths, it means being very physical.
Bela Karolyi was banned for "unspecified" reasons.
There are many reasons for this. It is most often blamed on religious texts, and while misinterpretation may be partially responsible, it is not the whole truth. A lot of it has to do with the idea that the West (the US in particular) has the best governing practices and also the West's inferred desire to force their ideologies upon other (non-Western) countries. Many extremist groups are about resisting the West and preserving tradition, however terrible their methods might be.
Nothing in any founding document protects them and they are groups that cause problems. However, they are not illegal until there is a law that specifically says they are outlawed.
It led the United States to offer weapons to extremist leaders who fought against the Soviet occupation of Afghanistan
Yes, "Mein Kampf" is banned in India. The book, written by Adolf Hitler, promotes extremist ideologies and is prohibited by the Indian government to prevent the spread of hate speech and incitement to violence.