The pigeon pea[1] (Cajanus cajan) or toor dal is a perennial legume from the family Fabaceae native to the Eastern Hemisphere.

[3]: 5941 The scientific name for the genus Cajanus and the species cajan derive from the Malay word katjang (modern spelling: kacang) meaning legume in reference to the bean of the plant.

[29][30] In Latin America,[31] they are known as guandul or gandul in Spanish, and feijão andu or gandu in Portuguese all of which derive from Kikongo wandu or from Kimbundu oanda; both names referring to the same plant.

[41] In Suriname they are known as wandoe[42] or gele pesi,[43] the former of which is derived from the same source as its Spanish and Portuguese counterparts, the latter of which literally translates to 'yellow pea' from Dutch and Sranan Tongo.

[49] By at least 2,800 BCE in peninsular India,[50] where its presumptive closest wild relatives Cajanus cajanifolia occurs in tropical deciduous woodlands, its cultivation has been documented.

[53] From India it may have made its way to North-East Africa via Trans-Oceanic Bronze Age trade that allowed cross-cultural exchange of resources and agricultural products.

[54] The earliest evidence of pigeon peas in Africa was found in Ancient Egypt with the presence of seeds in Egyptian tombs dating back to around 2,200 BCE.

[55] From eastern Africa, cultivation spread further west and south through the continent, where by means of the Trans-Atlantic slave trade, it reached the Americas around the 17th century.

Being a legume capable of symbiosis with Rhizobia, the bacteria associated with the pigeon pea enrich soils through symbiotic nitrogen fixation.

[72] The crop is cultivated on marginal land by resource-poor farmers, who commonly grow traditional medium- and long-duration (5–11 months) landraces.

[73] Legumes, which provide highly nutritious products and contribute to soil fertility through biological nitrogen fixation, are one of the most important crops in mixed crop-livestock systems.

[70] Plant-growth promoting rhizobacteria (PGPR), together with strains of Rhizobium, can enhance growth and nitrogen fixation in pigeon pea by colonizing thenselves in the plant nodules.

Using a single bioinoculant shows benefits, but mixed communitites of different bioinoculatns have a greater positive impact on nodulation, plant dry mass, as well as shoot and root length.

[88] Over 50 years of pigeonpea breeding has resulted in genetic improvements, disease-resistant varieties, a reduction in crop maturity from 300 to less than 90 days, and the introduction of the first legume hybrid technology, which has increased yields by 30-50%.

[89] John Spence, a botanist and politician from Trinidad and Tobago, developed several varieties of dwarf pigeon peas which can be harvested by machine, instead of by hand.

It also received support from the CGIAR Generation Challenge Program, US National Science Foundation and in-kind contribution from the collaborating research institutes.

There was a controversy over this as CGIAR did not partner with a national team of scientists and broke away from the Indo American Knowledge Initiative to start their own sequencing in parallel.

In combination with cereals, pigeon peas make a well-balanced meal and hence are favored by nutritionists as an essential ingredient for balanced diets.

[98] In Kenya and throughout the Swahili-speaking region of East Africa, pigeon peas are utilized in dishes such as mbaazi na mahamri, that is usually served for breakfast.

[99][100] In the Enugu state of Nigeria, and igbo dish called Ẹchịcha or Achịcha is made with palm oil, cocoyam, and seasoning.

It is a savory soup with rich flavors coming from the pigeon peas, smoked pork preferably the legs or tail, and souring agent called batuan.

[108][109][110] In the Dominican Republic, a dish made of rice and green pigeon peas called moro de guandules is a traditional holiday food.

A variety of sancocho is also made based on green pigeon peas that includes poultry, pork, beef, yams, yucca, squash, plantain and others.

[112] In Puerto Rico, arroz con gandules is made with rice and pigeon peas and sofrito which is a traditional dish, especially during Christmas season.

[115] Trinidad and Tobago and Grenada have their own variant, called pelau, which includes either beef or chicken, and occasionally pumpkin and pieces of cured pig tail.

[123] In the Congo pigeon peas are utilized as one of the main food forest and soil improvement crops after using a slash-and-burn fire technique called maala.

In Oman, pigeon pea is used to treat chronic diseases, and in traditional Chinese medicine it is used to relieve pain and control intestinal worms.

The widespread traditional medicinal use of the plant is attributed to its rich content of phenolic compounds, which have antiviral, anti-inflammatory, antioxidant, hypocholesterolemic and hypoglycaemic effects.