Haplogroup I-Z63

Haplogroup I-Z63, also known as I1a3 per the International Society of Genetic Genealogy ('ISOGG), is a Y chromosome haplogroup. It is correlated with a DYS456 value inferior to 15, but there are exceptions.
I-Z63 is most common in England, Scotland, Germany, Fennoscandia, Iberia and Poland. Its progenitor is assumed to have lived in Jutland at around 2500 BCE. Within Fennoscandia, I-Z63 has a particularly strong association with Finland. To date, ancient I-Z63 has been found archeologically in Poland and Italy.
Origins.
On the basis of analysing samples of volunteers in YDNA sequencing, the YDNA analysis company YFull estimated that I-Z63 formed 4,600 years ago (2600 BC) (95% CI 5,100 <-> 4,000 ybp) with a TMRCA (Time to Most Recent Common Ancestor) of 4,400 years (95% CI 4,900 <-> 3,900 ybp) before present.
Geographically I-Z63 is believed to have arisen in or near what is now Denmark (based in part on the current distribution of this haplogroup). The current distribution of I-Z63 shows that there is a very high concentration of I-Z63 on the British Isles. At the same time, the archeological record presents a strong association of I-Z63 to the Wielbark culture and by extension with the Goths. There is a proposed link between the Goths and British migration, the so-called "Jutish Hypothesis". The "Jutish hypothesis" claims that the Jutes may be synonymous with the Geats of southern Sweden or their neighbours, the Gutes. The evidence adduced for this theory includes:
The Jutes invaded and settled in southern Britain in the late 4th century during the Age of Migrations, as part of a larger wave of Germanic settlement in the British Isles. The Jutish migration to Britain may explain the high concentration of I-Z63 found in modern Britain. However, I-Z63 is notably sparse among modern volunteer testers from Denmark. This is surprising because, in a geographical sense, Denmark encompasses the ancient homeland of the Jutes. Foreign invaders displacing the Jutes from their ancient homeland may explain the relative lack of I-Z63 in Denmark. Even in the year 945, the peoples of Jutland were threatened by foreign invaders (yet ironically were posing a threat to other groups elsewhere, such as in England). In 945 King Hacon of Norway arrived in Jutland and slew many of the people there, sending the survivors “far up into the land”. The current distribution of I-Z63 clearly shows that while there is a near absence of I-Z63 in modern Denmark, sizable numbers of I-Z63 men live today in Finland, Norway, Sweden and Aland.
Based on the combined evidence, the preferred current working hypothesis puts the progenitor of I-Z63 in ancient Jutland around the year 2000 BCE.
Archeological Record.
The I-S2077 subclade of haplogroup I-Z63 was sampled on an elite warrior buried in Bodzia (Poland) in a rich burial from ca. 1010-1020 AD. All artefacts there indicate a strong relation to the Kievian Rus ruling elite, so this man who probably succumbed to combat wounds, was in a close relationship with the Kievian Prince, Sviatopolk the Accursed (son of Vladimir the Great), married to a daughter of the Polish king Boleslaw the Great (Burisleifr from the Scandinavian sagas). The cemetery in Bodzia is exceptional in terms of Scandinavian and Kievian Rus links. The Bodzia man (sample VK157, or burial E864/I) was not a simple warrior from the princely retinue, but he belonged to the princely family himself. His burial is the richest one in the whole cemetery, moreover, Strontium analysis of his teeth enamel shows he was not local. It is assumed that he came to Poland with the Prince of Kiev, Sviatopolk the Accursed, and met a violent death in combat. This corresponds to the events of 1018 AD when Sviatopolk himself disappeared after having retreated from Kiev to Poland. It cannot be excluded that the Bodzia man was Sviatopolk himself, as the genealogy of the Rurikids at this period is extremely sketchy and the dates of birth of many princes of this dynasty may be quite approximative.
I-Z63 has been traced to the Kowalewko burial site in Poland which dates to the Roman Iron Age. In 2017 Polish researchers could successfully assign YDNA haplogroups to 16 individuals who were buried at the site. Out of these 16 individuals three belonged to haplogroup I-Z63, and in particular subclade I-L1237. The Kowalewko archeological site has been associated with the Wielbark culture. The Wielbark culture in turn has been associated with the Goths. Therefore the subclade I-L1237 of I-Z63 may be seen somewhat as a genetic indicator of the Gothic tribe of late antiquity. It has to be noted, however, that I-L1237 predates the Gothic tribe and it is also found in high concentration in other places not directly connected to the Goths (especially the British Isles). However, there is an academic theory that the Gothic tribe is connected to British migration through the so-called "Jutish Hypothesis", which would explain why I-L1237 is so strongly associated both with British migration and with Gothic migration patterns.
I-Z63 was found in a late 6th Century cemetery in Collegno, Italy, near the city of Torino. The Collegno burial site is associated with Gothic and Lombard remains and dated to the late 6th Century. The remains belong to I-FT104588, which is a subclade of I-BY316/I-Y7626. This discovery adds another historical connection of I-Z63 to the Gothic migrations of the early Medieval Period.
Another I-Z63 archeological find at the Crypta Balbi site in Rome was dated to Late Antiquity (400-600 CE) and reported to be Y-DNA haplogroup I-Y7234. Interestingly, Lombard-associated ornaments have been excavated at this site, pointing to connections with central Europe. Additionally, five of the seven individuals from this site, including the I-Z63 individual, were classified by ChromoPainter into a cluster with more haplotype sharing with central/northern Europeans.
Significant Subclades.
Even though I-Z63 itself is not considered a Nordic haplogroup, it does with I-BY316/I-Y7626 contain a significant Nordic subclade, whereby I-BY316 is heavily weighted towards Finland, Sweden, Norway, Iceland and Aland.
Prominent members of I-Z63.
Sviatopolk the Accursed (son of Vladimir the Great) is believed to have carried the I-S2077 subclade of Z63. By patrilineal extension this may also make Rurik an I-Z63. 
James "5th Laird of Cadzow" Hamilton is thought to have carried the I-L1237 subclade of Z63.
William Bradford, Mayflower passenger.