The phrase "concentrated primarily" is correct and usable in written English.
You can use this phrase when describing the focus or emphasis of something. For example, "My research was concentrated primarily on the historical background of the region."
The duo have concentrated primarily on music written for one piano, four hands.
Numerous islands, concentrated primarily in the north, are diverse in origin and landscape.
Its Guernsey-based Biotechnology Investments concentrated primarily on small US companies floated in IPO (initial public offering) issues.
Most past theoretical models and experimental investigations have concentrated primarily on the later period.
The private bank issuing of notes today in the world, I believe, is concentrated primarily in two countries.
The American epidemic is still concentrated primarily in gay men, and is growing rapidly worse among young black gay men.
It concentrated primarily on banking, but also questioned whether trustees had sufficient skills to weather the impact of the financial crisis and what the longer-term outlook was.
Indeed, rates dropped in all regions of the country, although the new laws are concentrated primarily in the Midwest and the South.
The Americas" series concentrated primarily on popular African Diaspora forms of North, Central and South America and their underappreciated connections with contemporary Western concert dance.
The Emirati leadership is facing the prospect that they could be dragged into the controversy that hitherto has been concentrated primarily on Russia.
In Italy the Rococo style was concentrated primarily in Venice, where it was epitomized by the large-scale decorative paintings of Giovanni Battista Tiepolo.
