"Before Present" means before 1950. The most commonly used convention in radiocarbon dating. "Present" referring to the year 1950 AD. 1950 is the date that the calibration curves were established.

BP stands for "Before Present." It is a term used in radiocarbon dating to describe the age of an object or event in years before the present day.

Explanation:

Radiocarbon dating is a method used to determine the age of an object by measuring the amount of carbon-14 it contains. Carbon-14 is a radioactive isotope of carbon that is formed in the atmosphere and taken up by living organisms. When an organism dies, the amount of carbon-14 in its tissues begins to decay, and the rate of decay can be used to calculate the age of the object.

To express the age of an object in radiocarbon dating, scientists use the term "Before Present." The "present" in this context refers to the year 1950, which is when the radiocarbon dating method was first developed. This is because prior to 1950, the amount of carbon-14 in the atmosphere was relatively stable, and so the ratio of carbon-14 to other isotopes in organic matter was also stable.

Therefore, if an object has a radiocarbon age of 2000 years BP, it means that it is 2000 years older than the year 1950. So, the year of its age would be 1950-2000 = 50 BCE.

In summary, BP stands for "Before Present," which is a term used in radiocarbon dating to describe the age of an object or event in years before the present day, with the "present" being defined as the year 1950.

What I understand is for 200BC in Before present is 2020(present year)+200=2200BP, Simply reversely counting the years from the present year.

But seriously I couldn't able to understand the given explanation below the answer,if anyone understand it please enlighten me.