Original: During British Rule Shakargarh Tehsil was an administrative subdivision of Gurdaspur District, in 1947 the majority of the district went to India with Pakistan retaining the tehsil of Shakargarh which then became a subdivision of Sialkot District.
Simplified: The line divided Shakargarh from the rest of Gurdaspur district (which then became part of India). Shakargarh then became part of Sialkot District, however when Narowal District was created in 1991, Shakargarh became part of that district.