Territorial behavior is a typical unconscious human behavior, and it has attracted great academic attention since it was introduced into the field of organizational behavior.Individuals are likely to engage in territorial behavior, and their feelings, attitudes, and other work behaviors will be affected.Actually, this phenomenon and influence also exist at the team level.Team′s external territorial behavior means that team members express psychological ownership of valuable organizational things to other teams.The difference in behavioral recipients enables team members to clearly understand the advantages of being members of their teams, generate a strong sense of team consciousness and identify themselves as a part of the team.Thus, a team′s external territorial behavior can create a harmonious and friendly team climate.As such, team members are generally more willing to share their knowledge with each other.There is increasing attention on how a team′s external territorial behavior reduces individual territorial behavior.#br#This study focuses on the impact of teams′ external territorial behavior on team knowledge sharing and the underlying mechanisms.Existing studies have shown that team psychological safety climates have a significant influence on team knowledge sharing.Factors such as the degree of familiarity between members and insider perception can facilitate a team′s psychologically safe climate.Besides, since the intensity of teams′ external territorial behavior on psychological safety climate is constrained by some team characteristics, the study incorporates team mindfulness into the theoretical model to examine its boundary effect.Drawing on social identity theory, it develops a moderated mediation model to examine the relationship between team external territorial behavior and team knowledge sharing, the mediating effect of team psychological safety climate, and the moderating effect of team mindfulness with data from 329 employees nested in 64 teams.#br#The results show that (1) team external territorial behavior is positively related to team knowledge sharing; (2) team psychological safety climate plays a mediating role in this process; (3) team mindfulness positively moderates the effect of team external territorial behavior on team psychological safety climate.Specifically, when the level of team mindfulness is low, the influence of team external territorial behavior on team psychological safety climate and the mediating effect of team psychological safety climate are not significant.However, when the level of team mindfulness is high, the relationship between team external territorial behavior and psychological safety is stronger, and the mediating effect of team psychological safety climate is strengthened.#br#The theoretical contributions of this study are threefold.First, drawing on social identity theory, this study enriches the relevant research on territorial behavior by conducting a team-level investigation and expands the mechanism of the positive effect of territorial behavior.Extant research on territorial behavior has focused on its negative consequences, such as knowledge hiding, relationship conflict, and interpersonal conflict.This study reveals that the collectively outward nature of team external territorial behavior can also generate positive effects for the teams, which contributes to team functioning.Second, this study illustrates why team external territorial behavior can promote team knowledge sharing, and verifies the mediating effect of team psychological safety climate.There are limited existing studies discussing the influence of territorial behavior on the internal climate of a team.By arguing that team behavior can shape the team climate and then influence the behavior of team members, this study explains why team external territorial behavior triggers the occurrence of team knowledge sharing behavior.Third, by proving the moderating effect of team mindfulness, this study demonstrates under what circumstances the effect of team external territorial behavior on the psychological safety climate of the team could be strengthened.The concentration of a team on the current issue and the way of processing information are different.Team mindfulness means that the team can focus on the current issue and deal with it in a non-judgmental way, which enables team members to pay more attention to the team task and reduce interpersonal conflicts.Therefore, team mindfulness can strengthen the effect of team external territorial behavior on psychological safety climate, provide a good boundary condition for the process of team external territorial behavior, and understand when the positive effect of team external territorial behavior on the team psychological safety climate is more salient.#br#