Complex attributive sentences in the Spanish language of the medieval period are characterized by a vague expression of the degree of syntactic subordination. During the XII-XVI
centuries there is a process of constant enrichment of meanings and forms of complex attributive sentences. The final formation of the structural organization of a complex attributive sentence ended in the XVII century, in the period of unification and formation of the national Spanish language.
Starting from the Old Spanish period, the externally formal homogeneity of models of a complex attributive sentence is disturbed by deep internal complications of semantic connections between the main and subordinate parts. Thus, in the Middle Spanish period, a complex attributive sentence gradually reformatted its structural organization by strengthening the contact position of the nominal center of subordination with the conjunctions and strengthening bilateral links between predicative components, which further contributed to the normalization of the position of the subordinate part.
On the other hand, there is an intensive mutual replacement of some conjunctions with
others.
In the Old Spanish period, the conjunctions bigan to lose their uncoordinated lexical correlation between the correlative word and the supporting noun in the main part. This trend
contributed to the consolidation of the structural organization of a complex attributive sentence, which was realized in the early Spanish period.