Short answers, pulled from the story.
Gujranwala is Pakistan's fifth-largest city and third-largest industrial centre, after Karachi and Faisalabad. It is nicknamed the "City of Wrestlers" and is famous for its cuisine, historical significance, and its role in the so-called Golden Triangle of industrial cities alongside Sialkot and Gujrat. The city contributes approximately 5% to Pakistan's national GDP.
Yes, Ranjit Singh, who founded the Sikh Empire, was born in 1780 in Gujranwala's Purani Mandi market. He maintained Gujranwala as his capital after rising to power in 1792, before moving the seat of the empire to Lahore in 1799 after capturing it from the Durrani Afghans.
Riots erupted in Gujranwala in April 1919 following the Jallianwala Bagh massacre in Amritsar, and they ranked among the most violent responses to that event across all of British India. The city's railway station, Tehsil Office, Clock Tower, Dak Bangla, and courts were damaged or burned, destroying much of the city's historical record. The Royal Air Force under Reginald Edward Harry Dyer used machine-guns mounted to low-flying aircraft and aerial bombardment against protestors.
Gujranwala is Pakistan's leading centre for sanitary fittings, with over 200 producers, and is home to more than 60 auto-parts manufacturers and roughly 150 enterprises in the electric-fan industry. The city ranks third nationally in iron and steel manufacturing, and has also been a centre of hosiery manufacturing since refugees from Ludhiana settled there after Partition in 1947. An estimated 6,500 small and medium enterprises and 25,000 cottage units operated in and around the city as of 2002.
Gujranwala was the site of some of the worst Partition violence in Punjab. On the 23rd of September 1947, rioters attacked a train of Hindu and Sikh refugees near Kamoke, killing 340 people. By March 1948, over 300,000 Muslim refugees had been resettled in Gujranwala District, and the number of registered factories grew from 39 in 1947 to 225 by 1961 as refugee communities from Ludhiana and Patiala introduced new trades.
The Golden Triangle refers to three neighbouring industrial cities in northeastern Punjab, Pakistan: Gujranwala, Sialkot, and Gujrat. The term describes their relative prosperity and export-oriented industrial base. The Sialkot International Airport, Pakistan's first privately owned commercial airport, built in 2007, serves the entire Golden Triangle region.