Guarded caravans, each with their own envoys of diplomats and scouts, are deployed past meaningful borders of the league- that is, borders that denote not only the limits of the league's protection, but borders with a meaningful population past them. The scouts are sent ahead of the caravans, their intent being to locate foreign tribes or foreign tribes' scouts. In the scenario that they do make contact, their jobs are to make it clear that they come as representatives and diplomats, rather than a hostile force. The caravans carry furs, wines, and metals - offers of goodwill. Offers of mutual prosperity.
The goal of these expeditions is to establish good relations with the tribes who, while historically born from the same culture as the League's tribe, are nevertheless at least a couple branches away on the tribal heritage tree. Trade, and if they're willing, alliances, are offered alongside the gifts.
On the internal side of things, there is an increased focus on infrastructure. Cities'
paved roads are improved and expanded, whilst the vast majority of the agrarian countryside simply develops its beaten down dirt roads. Some hamlets employ the use of rounded stones in their roads, though it's generally only to reduce erosion. Research shifts to horticulture.