Final answer:
The Magna Carta was a specific piece of evidence that demonstrates a new form of government in the period from 1250 CE - 1450 CE.
Step-by-step explanation:
One example of a new form of government during the period from 1250 CE to 1450 CE is the Magna Carta. The Magna Carta, signed in 1215, introduced the principles of due process and limited the powers of the English monarchy. It codified the idea that no free man could be penalized without a lawful judgment from his peers. This concept has had a lasting impact and was later adopted by the United States in its own constitution. The Magna Carta contributed to a social order that may have contributed to England's GDP per capita being second only to that of northern Italy in 1348.