O nascimento de Christ é um grande marco. Porém in English ele é represented de um modo um pouco different:
BC = Before Christ
* BC represents the years BEFORE Christ was born;
* BC deve estar sempre AFTER the number.
Eg.: Cleopatra died in 30 BC in Alexandria. She was 39 years old.
AD = Anno Domini
* Anno Domini means “the year of our Lord” in Latin;
* AD represents the years AFTER Christ was born;
* AD deve estar sempre BEFORE the number.
Eg.: This Roman painting is from the year AD 1.
Wanna know more? Access the original https://simple.wikipedia.org/wiki/Anno_Domini to expand your culture.