Sialkot (Punjabi, Urdu: سيالكوٹ) is a city located in Punjab, Pakistan. It is the capital of the Sialkot District and the 12th most populous city in Pakistan. The boundaries of Sialkot are joined by Jammu in the north east, the districts of Narowal in the southeast, Gujranwala in the southwest and Gujrat in the northwest.

Sialkot is believed to be the successor city of Sagala, the capital of the Madra kingdom which was destroyed by Alexander the Great in 326 BCE. It was made capital of the Indo-Greek kingdom by Menander I in the 2nd century BCE — a time during which the city greatly prospered as a major center for trade and Buddhist thought. In the 6th century CE, it again become capital of the Taank Kingdom, which ruled Punjab for the next two centuries. Sialkot continued to be a major political center until it was eclipsed by Lahore around the turn of the first millennium CE. Sialkot was the capital of the Punjabi Muslim ruler Jasrat Khokhar who reigned over most of Punjab and Jammu in the early 15th century. Under the Mughal Empire, especially Mughal emperor, Aurangzeb's reign, Sialkot became known as a great centre of Islamic scholarship and thought, and attracted scholars because of the widespread availability of paper in the city.

Sialkot city was the birthplace of the poet and philospher Muhammad Iqbal, a leading figure of the Pakistan Movement. The city has been noted for its entrepreneurial spirit and productive business climate which have made Sialkot an example of a small Pakistani city that has emerged as a "world-class manufacturing hub." The relatively small city exported approximately $2.5 billion worth of goods in 2017, or about 10% of Pakistan's total exports. The city has been labeled as the Football manufacturing capital of the World, as it produces over 70% of all footballs manufactured in the world. Sialkot International Airport; Pakistan's first privately owned public airport is located 14km west of Sialkot.

Sialkot was the likely capital of the Madra Kingdom Sagala, Sakala (Sanskrit: साकला), or Sangala (Ancient Greek: Σάγγαλα) mentioned in the Mahabharata, a Sanskrit epic of ancient India, as occupying a similar area as Greek accounts of Sagala. The city may have been inhabited by the Saka, or Scythians, from Central Asia who had migrated into the Subcontinent. The region was noted in the Mahabharata for the "loose and Bacchanalian" women who lived in the woods there. The city was said to have been located in the Sakaladvipa region between the Chenab and Ravi rivers, now known as the Rechna Doab.

The Anabasis of Alexander, written by the Roman-Greek historian Arrian, recorded that Alexander the Great captured ancient Sialkot, recorded as Sagala, from the Cathaeans, who had entrenched themselves there. The city had been home to 80,000 residents on the eve of Alexander's invasion, but was razed as a warning against any other nearby cities that might resist his invasion.

The ancient city was rebuilt, and made capital by the Indo-Greek king Menander I of the Euthydemid dynasty, in the 2nd century BCE. The rebuilt city was shifted slightly from the older city, as rebuilding on exactly the same spot was considered inauspicious.

Under Menander's rule, the city greatly prospered as a major trading centre renowned for its silk. Menander embraced Buddhism in Sagala, after an extensive debating with the Buddhist monk Nagasena, as recorded in the Buddhist text Milinda Panha. the text offers an early description of the city's cityscape and status as a prosperous trade centre with numerous green spaces. Following his conversion, Sialkot developed as a major centre for Buddhist thought.

Ancient Sialkot was recorded by Ptolemy in his 1st century CE work, Geography, in which he refers to the city as Euthymedia (Εύθυμέδεια).