Re: This sentence is true ?
When referring to a race or nationality, such as in this context, people is used as a singular noun. It can be confusing, even to native speakers, because the word is almost always used as the plural of person.
"The Chinese are a very superstitious people." This is correct English.
To further confuse the issue, the plural of people in this context is -- you guessed it -- peoples.
"The many peoples of Indonesia speak over 300 different languages." Here, peoples refers to different groups or ethnicities of people within Indonesia. The sentence "The many peoples of the nation finally came together in peace" underscores that there are different races and ethnicities in the one nation.
Fish is similar, actually. When we talk about many fish in general, the word fish is both singular and plural. However, when we want to make clear that there are multiple species, we use fishes. ("The rift lakes of east Africa are home to all sorts of fishes.")
Things like this confuse even native speakers, so it's a good question to ask!
P.S. You wrote, "I have been knowing..." The verb know is typically not used in the continuous form, so simply, "I know..." would be correct. :)