Two thousand years ago the British Isles were inhabited by speakers of Celtic languages. These languages still survive in parts of Wales, Scotland, Ireland, and Brittany in France. The Celts were conquered by the Romans, and from 43 BC to about AD 410 the areas which are now England and Wales were part of the Roman Empire, and Latin was the language of government. Between the fourth and seventh centuries A. D., the Anglo-Saxons arrived from what is now northern Germany, Holland and Denmark, and occupied most of England, and parts of southern Scotland. In some parts of Wales, Scotland and Ireland, people still speak Celtic languages. The Anglo-Saxons spoke a Germanic language which forms the basis of modern English. This language was modified by the arrival of Viking invaders in the north and east of the country, who came from Norway and Denmark between the eighth and eleventh centuries. These Scandinavian settlers spoke Old Norse, which was related to Anglo-Saxon, and which is the parent language of modern Danish. These two invasions caused English to become "mixed" to some degree (though it was never a truly mixed language in the strict linguistic sense of the word; mixed languages arise from the cohabitation of speakers of different languages, who develop a hybrid tongue for basic communication). The mixing of the two languages greatly enriched the vocabulary of English. By the middle of the tenth century England had become a unified country under one king. Cohabitation with the Scandinavians resulted in a significant grammatical simplification and lexical enrichment of the Anglo-Frisian core of English. This Norman influence entered English largely through the courts and government. Thus, English developed into a "borrowing" language of great flexibility and with a huge vocabulary. Many Latin words for common objects therefore entered the vocabulary of these Germanic people even before any of these tribes reached Britain; examples include camp, cheese, cook, fork, inch, kettle. The Romans also gave English words which they had themselves borrowed from other languages: anchor, butter, chest, devil. The period when England was ruled by Anglo-Saxon kings, with the assistance of Anglo-Saxon clergy, was a period when the English language was alive and growing. Since it was used for legal, political, religious and other intellectual purposes, Old English coined new words from native Anglo-Saxon roots, rather than "borrowing" foreign words. In 1066 England was conquered by the French-speaking Normans, and French became the language of government. For the next three hundred years three languages co-existed. The aristocracy spoke French, the ordinary people spoke English, while Latin was used in the church. Modern English evolved from the mingling of the three tongues. Today English vocabulary is approximately half Germanic (from the Saxons and Vikings) and half Romance (from French and Latin). There are however considerable borrowings from other languages. A tendency for French-derived words to have more formal connotations has continued to the present day; most modern English speakers would consider a "cordial reception" (from French) to be more formal than a "hearty welcome" (Germanic). Another homely example is that of the names for meats, such as beef and pork from French boeuf and porc. The animals from which the meats come are called by Anglo Saxon words, such as cow and pig. This might be because Anglo-Saxon peasants raised the animals; Norman-French lords ate the meat. Modern English is often dated from the Great Vowel Shift, which took place mainly during the 15th century. English was further transformed by the spread of a standardised London-based dialect in government and administration and by the standardising effect of printing. By the time of William Shakespeare (mid-late 16th century) the language had become clearly recognizable as Modern English. English has continuously adopted foreign words, especially from Latin and Greek, since the Renaissance. As there are many words from different languages and English spelling is variable, the risk of mispronunciation is high, but remnants of the older forms remain in a few regional dialects, most notably in the West Country. English has changed so much in the last 1500 years that it would now be hardly recognizable to the Anglo-Saxons who brought the language across the North Sea. Although they would be able to recognize many individual words, they would not recognize the way those words are put together to make sentences. Old English, like modern German, was a highly inflected language, i. e. most words changed their endings or forms to show their relationship to other words in the sentence according to number (singular, plural), gender (masculine, feminine, neuter), case (subject, object), tense (past, future) etc,. Some modern English words still inflect, but much less so than in other European languages. The English verb 'to ride' inflects into five forms (ride, rides, riding, rode, ridden) whereas the equivalent German verb has sixteen forms. The English word 'the' has only one form, whereas other European languages would have several different forms. The trend towards simplicity of form is considered to be a strength of English. Another strength is the flexibility of function of individual words. This flexibility, together with a flexibility towards the assimilation of words borrowed from other languages and the spontaneous creation. of new words have made English what it is today, an effective medium of international communication. English has achieved this in spite of the difficulties caused by written English, which is not systematically phonetic. Approximately 350 million people speak English as their first language. About the same number use it as a second language. It is the language of aviation, international sport and pop music. 75% of the world's mail is in English, 60% of the world's radio stations broadcast in English and more than half of the world's periodicals are printed in English. It is an official language in 44 countries. In many others it is the language of business, commerce and technology. There are many varieties of English, but Scottish, Texan, Australian, Indian and Jamaican speakers of English, in spite of the differences in pronunciation, structure and vocabulary, would recognize that they are all speaking the same basic language.