As trumpets sounded a fanfare, Egyptian President Anwar Sadat arrived in Israel tonight carrying new proposals for peace between the Jewish state and its Arab neighbors.

The flag of Egypt fluttered over Ben Gurion Airport as Sadat bounded down the steps of his jetliner on a cool Israeli night to receive a warm greeting from Prime Minister Menahem Begin.

The two leaders, whose countries have fought four wars in the past 29 years, then stood stiffly side-by-side, looking somber and pensive, as the thunder of a 21-gun artillery salute punctuated the playing of the Egyptian and Israeli national anthems.

From the airport, Sadat and Begin drove in separate cars to the King David Hotel in Jerusalem, where they immediately plunged into their first round of discussions.

While no details of their talks were disclosed, Begin emerged smiling and told reports. "We had a very warm and cordial conversation. You can say that we like each other."

The two leaders will hold additional rounds of talks on Sunday and Monday, but the high-point of Sunday's activites will come in the late afternoon when Sadat makes his historic address to the Israeli Knesset.

Earlier Sunday, the Egyptian President will become the first Arab leader since the 1967 Mideast war to pray at Jerusalem's Al Aqsa Mosque, third holiest shrine Islam. Jordan's King Abdullah, the last Arab leader to offer to make peace with Israel was slain by Arabs while worshipping in Al Aqsa Mosque in 1951.

Security precautions for Sadat's visit were the tightest in Israeli history. More than 10,000 police, backed by thousands of soldiers, had taken up positions by early today, and all roads leading to Ben Gurion Airport were sealed off eight hours before his arrival.

Sadat's gleaming white jet with a red-and-gold stripe touched down in Israel at 7:59 p.m., one minute ahead of schedule. It was bathed in brilliant light as it taxied up to the reception area.

A particularly poignant moment occurred immediately following the playing of the anthems. An Israeli Army officer stepped up to Sadat, saluted, and said crisply: "Mr. President, the guard of honor of the Israeli Defense Forces is ready for your inspection."

As the Egyptian president strode slowly past the 72 Israeli cadets, Israelis sitting before televisions watching the unbelieve sight of an Arab leader inspecting their sons heard the commentator remark: "A new era has begun."

As Begin steered Sadat down a reception line of Israeli officials, the pomp and ceremony was abruptly transformed into what seemed more like a reunion of old friends.

He kissed former Prime Minister Golda Meir, then reaching his old adversary, Foreign Minister Moshe Dayan, Sadat broke into an ear-to-ear grin, gripped him by the shoulders, and greeted him as "Moshe."

The Egyptian president also had a warm greeting for Agriculture Minister Ariel "Arik" Sharon, who led the Israeli forces that counter-attacked across the Suez Canal in 1973.

"I wanted to catch you in the Sinal but I didn't succeed," he said in English.

When he came to Gen. Mordechal Gur, the Israeli chief of staff who warned last week that President Anwar Sadat's offer to visit might be a bluff and that Egypt was preparing for war, Sadat waggled a finger at him and said: "I fooled you."

"I'm living a dream. This isn't happening," said one Israeli journalist at the end of the arrival ceremony. There were no airport speeches.

Sadat and Begin went immediately to the Egyptian leader's headquarters in Jerusalem's King David Hotel. Sadat drove from Ben Guiron Airport with Israeli President Ephraim Katzir in an aromored Cadillac that Israel and borrowed from President Carter. It was urgently air-lifted here from the United States.

During the flight here from Cairo, Sadat told Walter Cronkite of CBS that he had a number of specific, substantive proposals to make to Israel. In another interview, with John Chancellor of NBC, Sadat said he was prepared to extend his stay here as long as was necessary.

Begin was also reportedly planning to make concrete proposals to Sadat. Israeli sources said there had been Israeli-Egyptian diplomatic communications before Sadat's arrival about specific proposals.

Sadat set only one condition for his visit to Israel - that he be allowed to address the Knesset. He acceded to a long list of Israeli suggestions for symbolic gestures during his stay. These included:

The laying of a wreath at the memorial to Israel's war dead.

A visit to Vad Yashem, the memorial to the 6 million Jews killed in Nazi concentration camps in World War II.

The flying of Israeli and Egyptian flags side by side.

The review of an Israeli military guard of honor upon his arrival.

The playing of two national anthems.

The acceptance of full protocol of a state visit, except for an offical state banquet.

Battalions of troops lined the road winding up through the Jerusalem hills from Ben Gurion Airport to the capital. As the motorcade passed populated areas, hundreds of children and Saturday night strollers cheered.

When Sadat arrived at the royal suite of the King David Hotel, he found the rooms filled with bouquets of flowers, many of them sent by ordinary Israel citizens.

At at the airport, Sadat's arrival at the hotel was met by spontanoeus bursts of applause. Although Israeli newspapers have been cautioning readers not to be swept away by the euphoria, the population here has been quasi-unanimous in its expression of public support for Sadat's grand gesture. Not even the parents of young men who have died in wars against the Egyptians have expressed hostility to the visit.

"This is what we have been waiting for," said a third generation Israeli woman. "We want peace. We're sick of living in fear of war."

A third grade class even cabled Begin to ask him to persuade Sadat to let them visit the pyramids, which they are currently studying about in school.

Arabs who live in Israel and in the occupied territories were much more reserved. Notably absent from the receiving line at Ben Gurlon Airport were Palestinian leaders from the occupied West Bank.

Israeli officials say that their worst security nightmare will come when Sadat goes to pray with the Moslem faithful Sunday at Al Aqas and the adjacent Dome of the Rock, from which the Prophet Mohammed is said to have ascended into heaven.

Large crowds of Moslems are expected to gather there at the mosque, in a setting where the Israeli security forces have traditionally maintained a virtual population of Jerusalem includes many sympathizers of the Palestine Liberation Organization, which has termed Sadat a traitor to the Arab cause.

In both Egypt and Israel, the press has been comparing Sadat's surprise visit with the surprise he achieved by launching the 1973 war.

Newspapers in both countries are also drawing the analogy between the Sadat visit and President Nixon's visit to China. In both instances, one of the diplomatic conduits may have been Romania. Begin today telephoned Romanian President Nicola Ceausecsu and President Carter to thank them for their assistance.

The process of preparing the visit began a week ago Wednesday with Sadat's extraordinary announcement before his Parliament that he was willing to come to Israel, to address its Paliament, the Knesset, in the interest of peace.

The Sadat speech was followed quickly by an emotional appeal by Begin to the Egyptian people pleading for friendship and peace. Later in interviews with Walter Cronkite of CBS, both Sadat and Begin made it clear there were no conditions to a Sadat visit.

A formal invitation from Begin was then transmitted to Sadat via American diplomats. Two days later, after what was an apparently stormy meeting in Damascus with Syria's President Assad, the Egyptian president sent his formal acceptance.

Begin cancelled a scheduled visit to Britain to comply with Sadat's wish to arrive today.

In a recent interview, Sadat termed the Middle East problem 70 per cent psychological and 30 per cent substance. He said he wanted to eliminate the psychological part of the conflict by explaining in person the Arab position to the Israelis.

There is intense speculation here over what Israel can give Sadat so that his mission does nsot appear as a failure. A member of the Egyptian advance party was quoted by an Israeli newspaper as saying," If he goes back empty handed, it's going to be horrible, horrible for you and him."

Many ordinary Israelis are treating the visit as if it means that a peace settlement has already been reached. School children interviewed by Israeli radio said that they were going to the route of the official motorcade to see "the man who was bringing peace."

So far, an Israeli official noted Begin in has had to give nothing in return to Sadat. Begin is to answer Sadat's speech in the Knesset Sunday. This is to be followed by an address by opposition leader Shimon Peres. The three speeches are each expected to run an hour or more.

Israeli leaders have indicated privately that they would have no basic problem returning more of the Sinai desert of Egypt. But, Sadat has indicated that, to be credible as an Arab leader, he must continue to press for major concessions to the Palestinians on the West Bank, an area where the Israelis are not prepared to be generous with territory.

Yigael Yadin, leader of the more left-wing component of Begin's governing coalition, said there is full agreement in the Israeli Cabinet that there can be no separate Palestinian state, that the PLO cannot take part in peace talks in Geneva and that Israel will not return to the borders it had before the 1967 war.

Egyptian officials said Sadat plans to stress that the Palestinian problem should be solved by the creation of a Palestinian entity linked to Jordan, a solution the Begin government is already on record as rejecting.