Çerkes

/tʃerkes/

Cases

SingularPluralWhen to use it
nominativeÇerkesthe CircassianÇerkeslethe Circassiansthe plain dictionary form — the doer of the sentence
genitiveÇerkesnithe Circassian'sÇerkeslenithe Circassians'the owner — whose it is
accusativeÇerkesnithe Circassian (as the object)Çerkeslenithe Circassians (as the object)a specific, known object — whom or what
dativeÇerkesgeto the CircassianÇerkeslegeto the Circassiansdirection or recipient — to where, to whom
locativeÇerkesdeat / in the CircassianÇerkesledeat / in the Circassianswhere it is; also having — mende bar, "I have it"
ablativeÇerkesdenfrom the CircassianÇerkesledenfrom the Circassianswhere it comes from; also "than" when comparing
When to use each case
nominative
the plain dictionary form — the doer of the sentence
genitive
the owner — whose it is
accusative
a specific, known object — whom or what
dative
direction or recipient — to where, to whom
locative
where it is; also having — mende bar, "I have it"
ablative
where it comes from; also "than" when comparing

The endings are the same ones the pronouns wear — that page explains when each case is used.

With an owner

One ownedSeveral owned
myÇerkesimmy CircassianÇerkeslerimmy Circassians
yourÇerkesingyour CircassianÇerkesleringyour Circassians
his / herÇerkesihis / her CircassianÇerkeslerihis / her Circassians
ourÇerkesibizour CircassianÇerkesleribizour Circassians
you all'sÇerkesigizyou all's CircassianÇerkeslerigizyou all's Circassians
theirÇerkesleritheir CircassianÇerkesleritheir Circassians

The overlap in the last rows is real, not a mistake: Çerkesleri can mean "his / her Circassians", "their Circassian", or "their Circassians" — context decides.