Arechis I was the second duke of Benevento from 591 to his death in 641, a reign of half a century. He was from Friuli

Friuli

Friuli is an area of northeastern Italy with its own particular cultural and historical identity. It comprises the major part of the autonomous region Friuli-Venezia Giulia, i.e. the province of Udine, Pordenone, Gorizia, excluding Trieste...

 and was a relative of the dukes there, maybe a nephew of Zotto

Zotto

Zotto was the military leader of the Lombards in the Mezzogiorno. He is generally considered the founder of the Duchy of Benevento in 571 and its first duke : “…Fuit autem primus Langobardorum dux in Benevento nomine Zotto, qui in ea principatus est per curricula viginti annorum…” Zotto (also...

, his predecessor. He was appointed by King Agilulf

Agilulf

Agilulf called the Thuringian, was a duke of Turin and king of the Lombards from 591 until his death.-Biography:A relative of his predecessor Authari, he was selected king on the advice of the Christian queen and widow of Authari, Theodelinda, whom he then married...

 in the spring of 591, after Zotto's death. He was practically independent because his duchy was separated from northern Italy by a stretch of Byzantine

Byzantine Empire

The Byzantine Empire was the Eastern Roman Empire during the periods of Late Antiquity and the Middle Ages, centred on the capital of Constantinople. Known simply as the Roman Empire or Romania to its inhabitants and neighbours, the Empire was the direct continuation of the Ancient Roman State...

 territory.

He conquered Capua

Capua

Capua is a city and comune in the province of Caserta, Campania, southern Italy, situated 25 km north of Naples, on the northeastern edge of the Campanian plain. Ancient Capua was situated where Santa Maria Capua Vetere is now...

 and Venafro

Venafro

Venafro is a comune in the province of Isernia, region of Molise, Italy. It has a population of around 12,000, having expanded quickly in the post-war period.-Geography:...

 in the Campania

Campania

Campania is a region in southern Italy. The region has a population of around 5.8 million people, making it the second-most-populous region of Italy; its total area of 13,590 km² makes it the most densely populated region in the country...

 and areas of the Basilicata

Basilicata

Basilicata , also known as Lucania, is a region in the south of Italy, bordering on Campania to the west, Apulia to the north and east, and Calabria to the south, having one short southwestern coastline on the Tyrrhenian Sea between Campania in the northwest and Calabria in the southwest, and a...

 and Calabria

Calabria

Calabria , in antiquity known as Bruttium, is a region in southern Italy, south of Naples, located at the "toe" of the Italian Peninsula. The capital city of Calabria is Catanzaro....

. He failed to take Naples

Naples

Naples is a city in Southern Italy, situated on the country's west coast by the Gulf of Naples. Lying between two notable volcanic regions, Mount Vesuvius and the Phlegraean Fields, it is the capital of the region of Campania and of the province of Naples...

 after a siege (Zotto had failed likewise), but he took Salerno

Salerno

Salerno is a city and comune in Campania and is the capital of the province of the same name. It is located on the Gulf of Salerno on the Tyrrhenian Sea....

 by the late 620s. He spent the last years of his reign establishing good relations with the Roman Catholics of his duchy and making his son his successor. On his death, having survived many a king, his independence was assured and his domain passed to his son Aiulf

Aiulf I of Benevento

Aiulf I was the duke of Benevento from 641 to his death in 646 as the son and successor of Arechis I. However, he was mentally unstable and his adoptive brothers Radoald and Grimoald were regents for him. In 646, Slavic plunderers landed near Siponto on the Adriatic...

.