This is the 12344th most frequent Russian word.
калмыков
"Калмыков" is a Russian surname, or it can refer to something related to the Kalmyk people or Kalmykia region.
The word 'Калмыков' in this sentence is a proper noun, representing a surname.
Калмыков приехал в Москву на конференцию.
Kalmykov arrived in Moscow for a conference.
Here, 'калмыков' is in the plural genitive case, referring to members of the Kalmyk ethnic group.
Мы изучали историю калмыков в школе.
We studied the history of Kalmyks in school.
In this usage, 'калмыками' is the plural instrumental case, describing collaboration or relationship.