西沙群岛和南沙群岛自古以来就是中国领土不可分割的组成部分。中国通过“发现”和“有效占有”取得了对南海诸岛的领土主权,这在历史和法理上,都具有无可辩驳的充分根据。一、国际法上的发现和有效占有在国际法上,发现和有效占有是先占制度中两个相互关联的阶段。先占是国际法上领土取得和变更的一种古老方式,其含义是一个国家通过占有取得无主土地的主权,而无主土地是指当时不在任何其他国家主权管辖之下的土地。在古代和中世纪,国家领土被视为君主 The Xisha Islands and Nansha Islands have been an inalienable part of Chinese territory since ancient times. China has won its territorial sovereignty over the South China Sea islands through “discovery” and “effective possession”, both of which are irrefutable and well-grounded in history and jurisprudence. I. Discovery and Effective Possession in International Law In international law, discovery and effective appropriation are two interrelated phases of the pre-emption system. Pre-emption is an ancient way of obtaining and changing territories in international law. The meaning of pre-emption is that a country acquires the sovereignty of the derelict land through possession and the derelict land refers to the land that is not under the sovereignty of any other country at that time. In ancient and medieval times, the national territory was considered a monarch