Final answer:
Historically, during significant periods such as post-World War I and World War II, Poland often had its agency for international representation hindered. After World War I, countries like Germany and Russia were initially excluded from the League of Nations. During World War II, despite alliances, Poland was left virtually alone to face Germany's invasion without immediate aid from Western Europe.
Step-by-step explanation:
In the historical context of Poland during the early and mid-20th century, when referring to entities that weren't able to send a representative, it likely pertains to the geopolitical situations surrounding both World Wars and the Cold War. During the formation of the League of Nations following World War I, several powerful countries including Germany and Russia were initially left out.
Furthermore, the Soviet Union had signed a non-aggression pact with Germany prior to World War II, which included a secret provision for the Soviet invasion of Poland. Consequently, as Germany began its invasion of Poland in 1939, Poland found itself without direct military assistance, as its Western allies, France and Great Britain, declared war on Germany but undertook no immediate action to support Poland.
Later, during the Cold War era, internal resistance against communist policies, such as those led by Lech Wałęsa and the Solidarity movement, demonstrated Poland’s nationalistic tendencies and desire for reform, which at times placed its representatives at odds with the Soviet-controlled Eastern Bloc's directives and, therefore, limited Poland’s own autonomy in international representation.