the western boundary of the lahngau was near present-day montabaur. to the west of the lahngau, extending to the rhine river, was the engersgau with its center in the neuwied basin. the northwestern border was marked by the watershed of the westerwald. northwest and north of the lahngau was the auelgau with its central settlements near the mouth of the sieg river and probably in the siegerland. north and northeast of the lahngau was the hessengau, the former settlement area of the chatti. like the lahngau, the hessengau would for a time be dominated by the conradines. southeast of the lahngau was the wettereibagau (later called the wetterau). south, at the watershed of the taunus mountains, was the boundary with the königssondergau. in the 1845 travel guide "le rhin," victor hugo notes: "then comes braubach, named in a charter of 933, fief of the counts arnstein of lahngau; an imperial city under rodolph in 1270, a domain of the counts of katznellenbogen in 1283; accruing to hesse in 1473; to darmstadt, in 1632, and in 1802 to nassau."