The mainland has relatively flat terrain, which is used to grow rice, while Langkawi is composed of mostly of uninhabited islands.

[9][10] Kedah borders the state of Perlis to the north and shares an international boundary with the Songkhla and Yala provinces of Thailand.

Other major towns include Sungai Petani (its largest urban area by population), and Kulim on the mainland, and Kuah on Langkawi.

The discovery of a temple, jetty remains, iron smelting sites, and clay brick monuments probably dating back to 110 AD shows that a maritime trading route with south Indian Tamil kingdoms was already established since that time.

[13] Ancient Kedah was first mentioned in the Tamil poem Paṭṭiṉappālai written at the end of the second century AD.

Apart from Kadaram, Kedah was known by various names at different times in Indian literature: Kataha-Nagara (in Kaumudi Mahotsava drama), Anda-Kataha (in Agni Purana), Kataha-Dvipa (in Samarāiccakahā), and Kataha (in Kathasaritsagara).

[14] In Middle Eastern literature, ancient Kedah was referred to as Qilah by Ibn Khordadbeh in the Book of Roads and Kingdoms, Kalah-Bar by Soleiman Siraf & Abu Zaid al Hassan in Silsilat-al-Tawarikh (travels in Asia), and Kalah by Abu-Dulaf Misa'r Ibn Muhalhil in Al-Risalah al-thaniyah.

[20] During the reign of Kulottunga I Chola overlordship was established over the Srivijayan province of Kedah in the late 11th century.

This later date accords with an account in the Malay Annals where a raja of Kedah visited Malacca during the reign of its last sultan seeking the honour of the royal band that marks the sovereignty of a Muslim ruler.

In the hope that Great Britain would protect what remained of Kedah from Siam, the sultan handed over Penang and then Province Wellesley to the British at the end of the 18th century.

In 1896, Kedah along with Perlis and Setul were combined into the Siamese province of Monthon Syburi which lasted until it was transferred to the British by the Anglo-Siamese Treaty of 1909.

Meanwhile, the northeastern towards the southeastern part of the state is particularly mountainous, especially in the districts of Padang Terap, Sik, Baling, Kulim and Bandar Baharu.

[49][50] Kedah is a heterogeneous state with native Kedahan Malays being the majority, along with significant Chinese, Indian, Siamese and Semang minorities.

The Orang Asli in Kedah consists of Kensiu and Kintaq people and are mainly to be found in the Baling district, as their community crosses there into the neighboring state of Perak.

The majority of the Indian population are Hindus (91.7%), with a significant minorities of numbers identifying as Christians (3.7%), Muslims (2.4%) and Buddhists (1.3%).

The non-Malay bumiputera community are predominantly Christians (39.7%), with significant minorities identifying as Muslims (26.9%) and Buddhists (26.3%).

[70][71] One of the main advantages is the low labour costs and the infrastructure in place with the North–South Expressway and the Penang International Airport close by.

[72] Under the Ninth Malaysia Plan, Kedah, along with neighbouring Perlis, Penang and Perak formed the Northern Corridor Economic Region (NCER) in 2007.

Additionally, the Keretapi Tanah Melayu (KTM) West Coast Line runs through mainland Kedah with six stops in total.

[74] The state has a campus of Universiti Utara Malaysia (UUM), which is located in Bandar Baru Sintok.

The university was established with the specific mission of providing a leadership role for management education in the country.

This state also has several boarding schools such as Sekolah Berasrama Penuh and MARA Junior Science College or MRSM.

This state also has several secondary Islamic schools (Sekolah Menengah Kebangsaan Agama) such as Tahfiz Model Ulul Albab or TMUA.