Sikh doctrine explicitly rejects caste and ethnic exclusivity, teaching that anyone regardless of background may take up the faith, and Sikh communities exist today well beyond Punjab, including sizable diaspora populations in the United Kingdom, Canada and the United States built up over more than a century of migration. In practice, however, the overwhelming majority of the world's Sikhs remain ethnically Punjabi, and the tradition's scripture, liturgy, festival calendar and much of its everyday devotional vocabulary are carried in Punjabi and Gurmukhi specifically, so that Punjabi identity and Sikh religious identity remain closely, though not absolutely, overlapping categories in a way scholarship on the tradition treats as historically inseparable from its founding context.
This overlap is itself a subject of ongoing discussion within the community: Punjabi Hindus and, historically, Punjabi Muslims share substantial cultural ground with Punjabi Sikhs even while differing in religion, and some Sikh institutions have worked deliberately to teach Sikhism's universal ethical claims to communities outside the Punjabi cultural sphere, including converts of other ethnic backgrounds, precisely because the tradition's own teaching holds that its message is not meant for one people alone even though its historical development and a large majority of its present adherents remain rooted in Punjab.