Question: Who discovered the country where Tengako can be found?

full_context: Document 1: Tuvalu: Captain John Byron passed through the islands of Tuvalu in 1764 during his circumnavigation of the globe as captain of the Dolphin (1751). Byron charted the atolls as Lagoon Islands. Keith S. Chambers and Doug Munro (1980) identified Niutao as the island that Francisco Mourelle de la Rúa sailed past on 5 May 1781, thus solving what Europeans had called The Mystery of Gran Cocal. Mourelle's map and journal named the island El Gran Cocal ('The Great Coconut Plantation'); however, the latitude and longitude was uncertain. Longitude could only be reckoned crudely as accurate chronometers were unavailable until the late 18th century.
Document 2: Marshall Islands: Spanish explorer Alonso de Salazar was the first European to see the islands in 1526, commanding the ship Santa Maria de la Victoria, the only surviving vessel of the Loaísa Expedition. On August 21, he sighted an island (probably Taongi) at 14°N that he named "San Bartolome".
Document 3: Tepuka: Tepuka is an island eighteen kilometers west of Fongafale, in the northwest of Funafuti, the main atoll of the Oceanian nation of Tuvalu. Te puka, or Pouka, is the name of a tree - "Hernandia peltata".
Document 4: Funamanu: Funamanu is a small narrow island that is part of Funafuti atoll in Tuvalu. It is a motu (islet) or very small island and is located 2.6 miles southwestward of the southwest tip of Funafuti. The islet is known to be covered in coconut trees which grow 70 feet high. Te Ava Pua Pua is the passage through the reef, with a least depth of 12.7 metres, between the islets of Funamanu to the north and Fale Fatu to the south, in the southeast of Funafuti atoll.
Document 5: Amatuku: Amatuku is an islet of Funafuti, Tuvalu on which the Tuvalu Maritime Training Institute is located. Access to Amatuku is from Tengako, which is the peninsula at the north end of Fongafale islet.
Document 6: Tuvalu: Tuvaluans are well known for their seafaring skills, with the Tuvalu Maritime Training Institute on Amatuku motu (island), Funafuti, providing training to approximately 120 marine cadets each year so that they have the skills necessary for employment as seafarers on merchant shipping. The Tuvalu Overseas Seamen's Union (TOSU) is the only registered trade union in Tuvalu. It represents workers on foreign ships. The Asian Development Bank (ADB) estimates that 800 Tuvaluan men are trained, certified and active as seafarers. The ADB estimates that, at any one time, about 15% of the adult male population works abroad as seafarers. Job opportunities also exist as observers on tuna boats where the role is to monitor compliance with the boat's tuna fishing licence.
Document 7: Guam: The indigenous Chamorros settled the island approximately 4,000 years ago. Portuguese explorer Ferdinand Magellan, while in the service of Spain, was the first European to visit the island, on March 6, 1521. Guam was colonized by Spain in 1668 with settlers, including Diego Luis de San Vitores, a Catholic Jesuit missionary. Between the 16th century and the 18th century, Guam was an important stopover for the Spanish Manila Galleons. During the Spanish -- American War, the United States captured Guam on June 21, 1898. Under the Treaty of Paris, Spain ceded Guam to the United States on December 10, 1898. Guam is among the seventeen non-self - governing territories listed by the United Nations.
Document 8: Tengako: Tengako is a peninsula at the north end of Fongafale islet of Funafuti, Tuvalu. At the end of the peninsula is Amatuku islet on which the Tuvalu Maritime Training Institute is located.
Document 9: Guam: The Chamorros, Guam's indigenous people, settled the island approximately 4,000 years ago. Portuguese explorer Ferdinand Magellan was the first European to visit the island on March 6, 1521. Guam was colonized in 1668 with settlers, like Diego Luis de San Vitores, a Catholic missionary. Between the 1500s and the 1700s, Guam was an important stopover for the Spanish Manila Galleons. During the Spanish–American War, the United States captured Guam on June 21, 1898. Under the Treaty of Paris, Spain ceded Guam to the United States on December 10, 1898. Guam is amongst the seventeen Non-Self-Governing Territories of the United Nations.
Document 10: Tuvalu: In 1568, Spanish navigator Álvaro de Mendaña was the first European to sail through the archipelago, sighting the island of Nui during his expedition in search of Terra Australis. In 1819 the island of Funafuti was named Ellice's Island; the name Ellice was applied to all nine islands after the work of English hydrographer Alexander George Findlay. The islands came under Britain's sphere of influence in the late 19th century, when each of the Ellice Islands was declared a British Protectorate by Captain Gibson of HMS Curacoa between 9 and 16 October 1892. The Ellice Islands were administered as British protectorate by a Resident Commissioner from 1892 to 1916 as part of the British Western Pacific Territories (BWPT), and then as part of the Gilbert and Ellice Islands colony from 1916 to 1974.
Document 11: Funafala: Funafala is an islet of Funafuti, Tuvalu that is inhabited by five families, with a church also located on the islet. Funafala means 'the pandanus of Funa', the name of a chief, after whom also the group has been named Funafuti.
Document 12: Funafuti: Funafuti is an atoll and the capital of the island nation of Tuvalu. It has a population of 6,025 people, making it the country's most populated atoll, with 56.6 percent of Tuvalu's population. It is a narrow sweep of land between 20 and 400 metres (66 and 1,312 feet) wide, encircling a large lagoon (Te Namo) 18 km (11 miles) long and 14 km (9 miles) wide. The average depth in the Funafuti lagoon is about 20 fathoms (36.5 metres or 120 feet). With a surface of 275 square kilometres (106.2 sq mi), it is by far the largest lagoon in Tuvalu. The land area of the 33 islets aggregates to 2.4 square kilometres (0.9 sq mi), less than one percent of the total area of the atoll. Cargo ships can enter Funafuti's lagoon and dock at the port facilities on Fongafale.
Document 13: Tuvalu: The next European to visit was Arent Schuyler de Peyster, of New York, captain of the armed brigantine or privateer Rebecca, sailing under British colours, which passed through the southern Tuvaluan waters in May 1819; de Peyster sighted Nukufetau and Funafuti, which he named Ellice's Island after an English Politician, Edward Ellice, the Member of Parliament for Coventry and the owner of the Rebecca's cargo. The name Ellice was applied to all nine islands after the work of English hydrographer Alexander George Findlay.
Document 14: Marshall Islands: Micronesian colonists gradually settled the Marshall Islands during the 2nd millennium BC, with inter-island navigation made possible using traditional stick charts. Islands in the archipelago were first explored by Europeans in the 1520s, with Spanish explorer Alonso de Salazar sighting an atoll in August 1526. Other expeditions by Spanish and English ships followed. The islands derive their name from British explorer John Marshall, who visited in 1788. The islands were historically known by the inhabitants as "jolet jen Anij" (Gifts from God).
Document 15: Tuvalu: In 1892 Captain Davis of the HMS Royalist reported on trading activities and traders on each of the islands visited. Captain Davis identified the following traders in the Ellice Group: Edmund Duffy (Nanumea); Jack Buckland (Niutao); Harry Nitz (Vaitupu); John (also known as Jack) O'Brien (Funafuti); Alfred Restieaux and Emile Fenisot (Nukufetau); and Martin Kleis (Nui). During this time, the greatest number of palagi traders lived on the atolls, acting as agents for the trading companies. Some islands would have competing traders while dryer islands might only have a single trader.
ground_truth: Álvaro de Mendaña
sub_queries: Tengako >> country Answer: Tuvalu
Who was the discoverer of Tuvalu ? Answer: Álvaro de Mendaña