verse using the unrhymed long line. Mirroring uncertainty over the evolution of alliterative verse in general, it is still uncertain as to whether this tradition developed from the unrhymed alliterative template or from rhymed verse forms on which the traditional alliterative stave was superimposed. While the poems in the thirteen-line stanza have generally been considered a part of the alliterative tradition, they have also been argued to be a related but distinct offshoot, incorporating elements of rhythm and metre that are in direct conflict with the conventions of unrhymed alliterative verse. The surviving stanzaic alliterative poems are generally of northern English provenance; some, such as Somer Soneday or The Three Dead Kings, are of very complex form. Development of the Revival The dialects shown in the surviving poems often point towards a northern and western provenance. The traditional interpretation of the Revival argues that such verse first began to be produced in the south-west Midlands, perhaps towards the start of the 14th century, and spread gradually northwards and eastwards, eventually becoming limited to the far north and Scotland by the close of the 15th century. This view suggests that the Revival was a largely self-contained movement whose "contacts with the metropolitan, Chaucerian tradition were slight". The words of the Parson in the prologue to Chaucer's Parson's Tale, that as a "Southren man" he cannot recite alliterative verse - "I kan nat geeste 'rum, ram, ruf' by lettre" - have often been taken as supporting evidence that alliterative verse was associated only with the north of the country. In more recent years medievalists have begun to challenge the idea that alliterative verse and its "revival" was an exclusively regional phenomenon, limited to the north and west of England. Although, as academic Ralph Hanna observes, the records of early alliterative poetry cluster overwhelmingly around the literary communities of Worcester, in the west, and York, in the north, alliterative poetry at least subsequently developed "as one competing form of a national, not regional, literature". This view interprets alliterative verse as part of the common literary culture of the time: although it was most appreciated in the rural north-west, several poems seem to have a definitely eastern (and in the case of The Blacksmiths, possibly urban) origin. The apparent flowering of the alliterative style in the period may have been due to social changes occurring in the wake of the Black Death, which would