110 EARLY MEDIEVAL SPAINeven penetrating as far south as Zaragoza. Both kings Sisebut (611/
12-620)and Suinthila (621-631) undertook substantial campaigns
against them. This may have been a contributory factor in the simul-
taneous migration of some of the Basque tribes out of the Pyrenees
into southern Aquitaine, where they came to pose a considerable
problem for successive Frankish kings.^34 However, this by no means
solved the problem for the Visigothic monarchy, and on at least two
occasions would-be usurpers in the north-east of the peninsula sought
Basque assistance in their schemes (654 and 673).
Whilst the difficulties posed by the failure of the Visigothic king-
dom to assimilate or control the Basques remained as considerable
for the seventh-century kings as for their predecessors, the danger to
be anticipated from other external enemies was in practice greatly
reduced. The Franks were generally embroiled in their own difficul-
ties for much of the time, and after the death of Theoderic II in 613
the threat of Frankish royal expeditions against Visigothic territories
was small, except when their aid was actively solicited, as in the case
of the assistance given by Dagobert I (623-639) to the rebel count
Sisenand in 631, which enabled the latter to overthrow King Suinthila
and take his throne.^35 But Frankish involvement in the affairs of the
Visigothic kingdom was slight and with the exception of the support
given to Sisenand in 631, which cost him 200,000 gold solidi, unsuc-
cessful. In 673, when the Franks came to the assistance of a .local
usurper, Paul, in Narbonne, they were easily driven out again by the
forces of the legitimate ruler as in 588.^36 But, although in practice
limited, the potential menace of the Franks may well have weighed
more heavily on the minds of the Visigothic kings than our meagre
sources can now reveal. The last details we are given on features of
the diplomacy carried on between the two peoples are to be found
in an exchange of letters dating from the reign of King Gundemar
(610-611/12) .37 The silence of the sources should not make us ig-
nore the possibility of more pacific commercial and cultural contacts
between the kingdoms. A letter of introduction and recommendation
to the ecclesiastical and secular authorities was given by Bishop
Desiderius of Cahors (d. 652) to a cleric who proposed to make a
journey into Spain.38 Such chance survivals do at least give credence
to the possibility of wider contacts than has usually been allowed by
those wedded to a belief in the essential isolation of Spain in the
Visigothic period.
Another old enemy of the realm whose menace may have pressed