the Aryan-speaking peoples moved into north India, about 2000 years BCE.,
they brought with them many variations of the Aryan language. Some of
these dialects developed literary forms (i.e., with grammar) later. The
most important dialect of these was Sanskrit. The word means "the
refined language" and its formalisation was due to Panini, who lived
about 500 years BCE.
Another language to arrive was Magadhi, spoken in the eastern part of north India. This was probably the language preferred and used by the Buddha. It was this language that came to be developed as a written language, which we now call "Pali".
The word "Pali" means "text" and its vocabulary has a special significance for the study of Buddhism, because its words have been well defined for the needs of the Buddha's teachings.
For example, in Pali the word "Dhamma", is reserved exclusively for the Buddha's ideas. On the other hand, "Dharma" in Sanskrit, has a very wide application - it applies to physical and moral teachings, teachings generally and even to the laws of nature.
Similarly with the Pali word "Kamma", this is the moral law as defined by the Buddha. In Sanskrit, the word "Karma" contains Hindu theistic ideas. Thus, it can be seen that Pali is the language of Theravada Buddhism.
Pali is not derived from Sanskrit. There are other, parallel dialects, such as Prakrit, and they only meet at their Indo-European origins. Another school of Buddhism, which emerged soon after the Buddha's death, used the classical language of India for the propagation of the Buddha's teachings - Sanskrit.
There is even a variety of Sanskrit
called "Buddhist Sanskrit"
It is the language of the Buddhist religion's record of teachings, the "The Tripitaka" (or The Three Baskets):
Pali is a written language, but it has no special script. Although trade-links were developed first, Buddhist monks and King's emissaries throughout the region developed its use. It was the "Lingua Franca" of the Buddhist countries of south and south-east Asia for well over a thousand years.
Each country subsequently developed
its own Pali literature and chronicles.
The personality of the Buddha is seen clearly in the Tripitaka. He "comes across" - speaking to us from down the ages, as a very intelligent, practical man who saw the great harm in anger and revenge. He strongly recommended all peoples to avoid hurting or injuring by word or deed, all other beings.