What do they mean by 'ethnicity'?

The other day I was filling up a form, and one of the questions was 'ethnicity.' I am aware of the immigration phenomena in cities such as London. It has happened to me lots of times in the New York in any kind of forms or applications (banks, schools, supermarkets, etc.)

I really wanted to write in the form 'Impossible to describe due colonization and globalization.' I think globalization started since the colonization of the Americas. But states, governments, and people(1) like to classify everything when somethimes is impossible.

Isn´t it racism? Who belongs nowadays to a pure ethnic line? I am sure there are a few, but just a few cases, and I am sure they are not europeans, "west men" or population in urban cities, they probably can be found in the indigenous rural areas of Mexico and the Americas, the tribes in the Amazonas, in the Pacific Islands, Asia or Africa untouchables by the "West Hand."

But how can I describe my ethnicity? Mestiza, with Yaqui and ancient spanish roots, which at the same time with celtic, roman, visigoths, arabic roots. I just went through all Spanish and Mexican history in two lines.

(2)

In the US I am a latina, and in the UK I am hispanic. That really pisses me off!


(1)"Grown-ups love figures... " The little Prince. Antoine De Saint-Exupéry. Wordsworth Classics. 1995, Great Britian. Refering to the need of statistics on everything and not seeing really essential matters on people and things. This causes conflicts such as wars.
(2) Charles Rangel is the Senior Congressman from New York.