There is no single art that can be considered the most demanding. Properly motivated, all of the Martial Arts can be very physically demanding, depending upon the effort put into it by the artist. Many arts are expected to be combined with cross training to include aerobic activities such as running and power building things like lifting weights.
They can all be very demanding. It is more on how much effort the practitioner puts into it then the specific style. While the fast moving ones are likely to provide a stronger aerobic work out, the slow ones still work the muscles hard.
No; most martial arts historians are in agreement, that it is wrestling which holds that honor. No, actually, the first real martial art is believed to be an inian martial art known as Kalarippayattu.
The most recent "established" martial art would have to be mixed martial arts or MMA. Unfortunately there is some debate to whether or not this an original martial art because it's just an amalgamation of several techniques from other martial arts. It combines everything from Judo to Greco-Roman Wrestling.
If you're asking where martial arts was born ... Then most believe it was born in China , and that , " Kung Fu" was the first martial arts form.
Boxing
Yes, Judo is a martial art that was based on JuJitsu.
Its not a martial art its a training drill.
It is Majest Martial Art.
ken-do in a form of martial art that uses primarily swords, although most martial arts use weapons at some level.
Samba (the most famous one) Pagode Forró Axé Frevo and some others
the most destructive type of martial art is taekwondo
Mixed Martial Art (MMA)