What prompted the great BodhiDharma to go to China to spread his teachings- why not at home in the first place. Was he the founder of
kalari payattu which has become somewhat unknown to us?
This is a long-standing mystery, described in many Zen Koans. Here are two Koans from the Gateless Gate that mentions it:
Kyogen said: "Zen is like a man hanging in a tree by his teeth over a precipice. His hands grasp no branch, his feet rest on no limb, and under the three another person asks him: `Why does Bodhidharma come to China from India?' If the man in tree does not answer, he fails; and if he does answer, he falls and loses his life. Now what shall he do?"
A monk asked Joshu, "With what intention did Bodhidharma come to China?" Joshu answered, "The oak tree in the front garden."
And here are three Koans from the Blue Cliff Record that mention it:
A monk asked Kyorin, “What is the meaning of the Patriarch’s coming from the West?” Kyorin said, “I am tired from sitting for a long time.”
Ryuge asked Suibi, “What is the meaning of the Patriarch’s coming from the west?” Suibi said, “Bring me a chin rest.” Ryuge brought one and gave it to him. Suibi took it and hit him. Ryuge said, “You may hit me as you like. After all there is no meaning to the Patriarch’s coming from the west.” Ryuge also asked Rinzai, “What is the meaning of the Patriarch’s coming from the west?” Rinzai said, “Bring me a sitting cushion.” Ryuge got one and gave it to Rinzai. Rinzai took it and hit him. Ryuge said, “You may hit me as you like. After all there is no meaning to the Patriarch’s coming from the west.”
A monk asked Great Master Ba, “Apart from the Four Phrases, beyond one hundred Negations, please tell me directly, Master, the meaning of Bodhidharma’s coming from the West.” Master Ba said, “I am tired today, I can’t explain it to you. Go and ask Chizo.” The monk asked Chizo about it. Chizo said, “Why don’t you ask our master?” The monk said, “He told me to ask you.” Chizo said, “I have a headache today, I can’t explain it to you. Go and ask Brother Kai.” The monk asked Brother Kai about it. Kai said, “I don’t understand nothing about that question.” The monk told Great Master Ba about it. Great Master said, “Chizo’s head is white, Kai’s head is black.”
He never went. For he had no purpose.
At least, that is what a Daoist perspective on the Koan would suggest as an "answer". And given that Chan (Zen) is in essence a Daoist expression of Buddhism, I think the response is likely correct.
Novice Zen monks are often called Unsui(雲水) in Japan. It translates to Cloud, Water. The name pays homage to the Zen Buddhist ideal of moving freely through life, without attachment, as in Zazen or Zen Buddhist meditation: we do not resist thoughts, nor cling to them. We sit perfectly still, in body and in mind. Why? The answer is quite simple: for absolutely no good reason whatsoever. Enlightenment, peace, happiness and whatever else one may expect to gain from Zazen are merely a desirable side effect. In the present moment, unless you can sit and breathe, for its own sake, you can never achieve Zazen.
Which brings us to my favorite version of the Koan:
Ryuge asked Suibi, “What is the meaning of the Patriarch’s coming from the west?” Suibi said, “Bring me a chin rest.” Ryuge brought one and gave it to him. Suibi took it and hit him.
Why did the Zen Master do this? It seems, at first, nonsensical. We can't blame the student for trying a different master:
Ryuge also asked Rinzai, “What is the meaning of the Patriarch’s coming from the west?” Rinzai said, “Bring me a sitting cushion.” Ryuge got one and gave it to Rinzai. Rinzai took it and hit him.
By now, it should be obvious why both Zen Masters did so: for absolutely no good reason whatsoever. It was purposeless, and the answer the student sought all along. In fact, he came so close to seeing it yet remained so far away. You can find the clue to the Koan in the answer the student gave each time, after being struck:
“You may hit me as you like. After all, there is no meaning to the Patriarch’s coming from the west.”
This is why the Blue Eyed Barbarian went to China. There was no grand purpose or spiritual mission. In that sense, he never went. No more than clouds go somewhere or water chooses to flow downstream. The patriarch's presence in China was a manifestation of Zen itself. He left for China because in that present moment, devoid of all attachment and illusory notions of self, going was what he was lead to do. Like a ball in a mountain stream, as one Zen poetic phrase puts it.
Or maybe I am reading too much into it and this is all wrong. Ultimately, there is no reason to worry about why Bodhidharma went to China. Just do more Zazen.
What prompted the great BodhiDharma to go to China to spread his teachings- why not at home in the first place.
Because he was a noble disciple who fulfilled the instruction of the Great Teacher:
"Go forth for the good of the many, for the happiness of the many, out of compassion for the world, for the welfare, the good and the happiness of gods and humans. Let no two of you go in the same direction. Teach the Dhamma which is beautiful in the beginning, beautiful in the middle and beautiful in the end. Explain both the letter and the spirit of the holy life, completely fulfilled and perfectly pure." ~ Vin.I,20 ~
What is known for sure about Bodhidharma is rather limited. New slices were added throughout time as the school and its self-image further evolved / developed.
Why he went to the Middle Kingdom to spread a new style or creed, is a classical question with high symbolic value. Answering it, or trying to, implies being part of the tradition.
Now the phenomenon of going 'across the mountains and over the seas' to spread the gospel, is a universal phenomenon. Sacred mission, missionary.
When you are a Buddha you live in a Choiceless Awareness. The reason Lord Buddha got inspiration to give the first sermon must be the same why Bodhidharma got inspiration to go to China. He didn't had a seperate sense of self like we do so the actions of the enlightened ones are very difficult to make sense using linear logic of causality. He could have as well sat in cave in India. So when he was asked who are you by the emperor, he said, 'I dont know'. Then what are the odds we can figure out why he left for China. Perhaps he liked the Tea, may be.