Question: Oswald of Sussex was an Ealdorman of the kingdom in what part of England?

Context paragraphs:
Sport in Sussex: Sport in Sussex forms an important part of the culture of Sussex.  With a centuries-long tradition of sport, Sussex has played a key role in the early development of both cricket and stoolball.  Cricket is recognised as having been formed in the Weald and Sussex CCC is England's oldest county cricket club.  Slindon Cricket Club dominated the sport for a while in the 18th century.  The cricket ground at Arundel Castle traditionally plays host to a Duchess of Norfolk's XI which plays the national test sides touring England.  The sport of stoolball is also associated with Sussex, which has a claim to be where the sport originated and certainly where its revival took place in the early 20th century.  Sussex is represented in the Football League by Brighton & Hove Albion and Crawley Town.  Brighton has been a League member since 1920, whereas Crawley was promoted to the League in 2011.  Sussex has had its own football association, since 1882 and its own football league, which has since expanded into Surrey, since 1920.  In horse racing, Sussex is home to Goodwood, Fontwell Park, Brighton and Plumpton.  The All England Jumping Course show jumping facility at Hickstead is situated 8 mi north of Brighton and Hove.

Ælfhelm of York: Ælfhelm (died 1006) was the ealdorman of Northumbria, in practice southern Northumbria (the area around York), from about 994 until his death.  An ealdorman (or earl) was a senior nobleman who governed a province—a shire or group of shires—on behalf of the king.  Ælfhelm's powerful and wealthy family came from Mercia, a territory and former kingdom incorporating most of central England, and he achieved his position despite being an outsider.  Ælfhelm first appears in charters as "dux" ("ealdorman") in about 994.

Kingdom of Sussex: Sussex ( ; Old English: "Sūþseaxna rīce" , "kingdom of the South Saxons") was a Saxon colony and later independent kingdom of the Saxons, on the south coast of England.

Sussex: Sussex ( ), from the Old English "Sūþsēaxe" (South Saxons), is a historic county in South East England corresponding roughly in area to the ancient Kingdom of Sussex.  It is bounded to the west by Hampshire, north by Surrey, north-east by Kent, south by the English Channel, and divided for many purposes into the ceremonial counties of West Sussex and East Sussex.  Brighton and Hove, though part of East Sussex, was made a unitary authority in 1997, and as such, is administered independently of the rest of East Sussex.  Brighton and Hove was granted City status in 2000.  Until then, Chichester was Sussex's only city.

Conquest Hospital: Conquest Hospital is a National Health Service hospital in St. Leonards-on-Sea near the borough of Hastings in East Sussex, England.  When Conquest Hospital opened in 1992 it was part of Hastings and Rother NHS Trust which, in 2002, merged with Eastbourne Hospitals NHS Trust to form East Sussex Hospitals NHS Trust.  Then in 2012 East Sussex Hospitals NHS Trust integrated with Community Services in East Sussex to form East Sussex Healthcare NHS Trust.

Oswald of Sussex: Oswald was an Ealdorman of Sussex, jointly with three former kings: Osmund, Ælfwald, and Oslac.

Andhun of Sussex: Andhun was an Ealdorman of Sussex under King Æðelwealh, who was slain by the Wessex prince Cædwalla, who invaded and ravaged Sussex.  Berhthun and Andhun succeeded in driving Caedwalla from the Kingdom.

Æthelwine, Ealdorman of East Anglia: Æthelwine (died 992) was ealdorman of East Anglia and one of the leading noblemen in the kingdom of England in the later 10th century.  As with his kinsmen, the principal source for his life is Byrhtferth's life of Oswald of Worcester.  Æthelwine founded Ramsey Abbey in 969, and Byrhtferth and Ramsey Abbey remembered him as "Dei amicus" (friend to God), but the monks of nearby Ely saw him as an enemy who had seized their lands.

Geography of Sussex: Sussex is a historic county and cultural region in the south of England corresponding roughly in area to the ancient Kingdom of Sussex.  It is bounded on the north by Surrey, north-east by Kent, south by the English Channel, and west by Hampshire, and is divided for local government into West Sussex and East Sussex and the city of Brighton and Hove.  The city of Brighton & Hove was created a unitary authority in 1997, and was granted City status in 2000.  Until then Chichester had been Sussex's only city.

History of local government in Sussex: The history of local government in Sussex is unique and complex.  Founded as a kingdom in the 5th century, Sussex was annexed by the kingdom of Wessex in the 9th century, which after further developments became the Kingdom of England.  It currently corresponds to two counties, East Sussex and West Sussex.

Supporting paragraphs: Oswald of Sussex Kingdom of Sussex
Answer: south coast