The biggest trading way across the Baltic Sea connected Semigallia with the West and East. Intensive trading relations were maintained across it in the 812th c.c.
Other important trading way of Semigallia was Daugava river. In the 1011th c.c. it was a part of the way from Normans to Greeks. From the 11th century this way became not only the object of trade but also the object of political interests of Russia.
Daugava trading way was particularly actively used from the 10th century when importation of Arabic silver started.
In addition to Daugava trading way, the Lielupė water and land way which in Scandinavian written sources is named Seimgol, in the chronicles of Henricus de Lettis Misa, in the Livonian Rhymed Chronicle Semegaller Aa, in others Semigallorum flumen or Semigallera, also was important to Semigallia. According to data of archaeological and written sources it may be supposed that the Lielupe way became especially important in trade between the late 10th early 11th c.c.
The Lielupe water and land way is forked into two parts Mūša and Nemunėlis.
The first branch Mūša turned to the southern end of Semigallia, the northern lands of Upper Lithuanians and Samogitians. At Kruoja river the Mūša way forked into two parts. The first of them quided to the West and emerged with the Venta, Mitau (Jelgava) Sidabra Šiauliai way. The second one, named the Kruoja branch, turned to the south, towards the upper reaches of Kruoja and guided to the Northern lands of Lithuanians.
The second branch Nemunėlis guided to the Southern Selonia and Lithuania. According to archaeological data it may be supposed that the Mūša Nemunėlis way became especially important in trade in the late 10th-early 11th c.c.
In Mežotne so called the Mežotne Salaspils land way began which crossed Daugava river at Salaspils and Iškile.
The other way which was especially important to western and southern Semigallians, northern and middle Curonians as well as to Samogitians was Venta river.
The trading way from the middle reaches of Venta along Vadakstė river guided to trading centres of western Semigallians between Vadakstė, Auce and Berže rivers, such as Rubas Rusyši, Auce, Bene.
Most probably from Rubas-Rušysi, Auce trading centres along Auce river towards its upper reaches the land way to Lielupe existed.
No less important was the land way from the Daugava mouth through the northern end of Semigallia to the Northern Curonia.
The Sidabra way became especially important in the system of Semigallian trading ways from the beginning of the 11th c. By it Sidabrė castle mentioned in written sources from the end of the 13th c. stood. From this semigallian centre the Sidabra way was divided to branches towards the South, East and West.
The southern branch along Sidabra river, towards its upper reaches and the confluence of Mūša and Kulpė rivers, guided trading centres of Šiauliai land (such as Jurgaičiai, Jakštaičiai-Meškiai (Bubiai) and so on) and then along Dubysa river to the Central Samogitia. The Eastern Branch, namely, Sidabrė Lieporai Žeimelis Mežotne, guided to eastern centres of Semigallia and connected with Daugava river.
The Western branch, namely, Sidabrė StungiaiŽagarė was used for communication with Žagarė the centre of Western Semigallia. It may be supposed that from this trading centre a trading way along Švėtė river towards its upper reaches existed.
The Žagarė Venta trading way was situated along Švėtė river towards its upper reaches and then to the lower reaches of Dabikinė river and guided to trading centres situated at Venta river.
Other way guided from MitauJelgava to Žagarė via Tervete. No less important was Mitau (Jelgava) Berže Curonia way.
In Bali Škerstaini the Bali Škerstaini the Northern Curonia started which guided to trading centres of the Northern Curonia.
The Švitinis, Virčiuvis and Mežotne Tervete Duobele way was used for local communications and connected the most important political and economical centres of Semigallians.
In the lower reaches of Daugava an important trading centre of that time Daugmale was situated. In addition to Scandinavians, Lyves, Semigallians, in Daugmale also Russians and Latgallians resided. According to archaeological materials it may be stated that Daugmale started to rise in the early 10th century. Its flourishing took place between the second half of the 10th the first half of the 11th c.c. The recession started in the middle of the 11th c. and this process continued up to middle of the 12th century when this trading centre finally fell into decay. It was bound with process which took place in the Baltic region when in the middle of the 12th c. the epoch of vikings came to its end. Instead of Scandinavians German merchants came.
10 km lower from Bauska where Lielupe river turns to the North, Mežotne the large political and economical centre of eastern Semigallians was situated. But here an import, in comparison with Daugmale, delayed. So, it may be stated that this centre appeared in the 9th c. and its flourishing took place in the 11th c. In the 12th c. the importance of Mežotne became less. But otherwise than Daugmale, it was not abandoned. Most probably, the cause of this was the fact that Mežotne was the political and administrative centre of the Eastern Semigallia. The concentration of political power maintained and supported its existence. On the other hand, processes within the lands of the Eastern Balts were of a great importance. Agricultural innovations come there later and the media of their realization was more favourable than within the lands of Western Balts, so it predetermined the progress of economy, stimulated a development of handicrafts and trade. Because of the favourable geographical position of Mežotne (by the way from Lithuania to region of Daugava and Estonia), the economical changes in neighbouring lands had to affect Upmalė region and its centres. Also it is necessary to keep in mind that trade with Russian lands did not decline like the one with Scandinavians. The economical development of Mežotne was greatly affected by crusades of German knights which started in the early 13th c. and destroyed the settled trading relations.
At Tervete rivulet Tervete the largest economical, political and administrative centre of the Western Semigallia was situated. The beginning of the flourishing of the centre is considered the early 11th c., mostly within the 11th late 12th c.c. Trade in Tervete fell into decay in the beginning of the 13th c. The causes were similar as in the case of Mežotne. Because of concentration of political powers in this centre it did not completely decay as the most of other centres of the Baltic region in the middle of the 12th c.
In addition to the above mentioned trading centres of Semigallia many smaller ones, such as Papilė and PavirvytėGudai, Dobele, Auce, RubasRusiši, Sidabrė, Žagarė, Kaireliai, Diržiai and so on, existed.